The Japanese Verb Stem (連用形): The Masu-Stem and Its Uses
The Japanese verb stem (連用形): the masu-stem and its uses sits at the center of how Japanese verbs build polite forms, attach derivational suffixes, coin new nouns, and link clauses in writing.1 Learners first meet it as "what is left when you drop ます." The same form is also a noun-maker (動き, 帰り, 始まり) and a literary clause-linker (雨が降り、風が吹く). In those two jobs, it never combines with ます.12
Overview
The form has several names because several traditions name it. It has several uses because the slot carries unusual weight in the Japanese conjugation paradigm.1 One derivation rule produces it from every verb class. Three productive jobs build on it from N5 reading practice into N1 written prose.342
The five names for one form
School grammar (学校文法) and academic linguistics call it 連用形 (ren'yōkei), literally "the form that attaches to 用言" (the inflecting word classes: verbs, i-adjectives, and na-adjectives).1 English-language textbooks call it the masu-stem or stem form.4 English-language theoretical linguistics calls it the i-form (because the godan reflex ends in an i-row syllable) and the continuative form (after its function).56
Tofugu's naming survey rounds up the other labels a learner is likely to meet in study materials: V-stem, ます form, conjunctive form, continuative stem, sentence-joining form.7 They all point at the same slot in the paradigm.
Where it sits in school grammar
Japanese school grammar arranges every conjugating verb into six 活用形 (conjugation-form) slots: 未然形, 連用形, 終止形, 連体形, 仮定形, 命令形.1 The 連用形 is the second slot, and it carries more syntactic load than any of the other five.
The slot name itself is descriptive: 連 ("link") + 用 (for 用言, "inflecting word") + 形 ("form"). It is the form that links to other inflecting words.1
The 連用形 is the attachment point for ます, た, て (via the godan euphonic onbin shift), たい, ながら, つつ, なさい, and historical auxiliaries such as き and けり. It also does the 中止法 clause-linking job and the noun-deriving job on its own.1
JLPT level by use
The form itself is N4 reference grammar.34 Its first appearance is even earlier: stem + ます is the first conjugation an N5 learner meets.4 The everyday auxiliaries (たい, ながら, やすい, にくい, すぎる, 方, なさい, そう) sit in the N5 to N4 band across standard textbook lessons.34
The 中止法 clause-linker is a Bunpro N3 grammar point and is regularly tested in JLPT N2 / N1 reading.2 Compound-verb productivity is lexical rather than a single JLPT point; the NINJAL 複合動詞レキシコン catalogues over 2,700 compound verbs in current Japanese.8 The stem-as-noun reading is also lexical and shows up piecemeal from N5 upward.9
How to form the masu-stem
The derivation rule is short and depends on the verb class. State it from the dictionary form rather than from the masu-form, because in two of the three productive jobs the stem never connects to ます at all.12
| Class | Rule | Examples |
|---|---|---|
| Godan (五段 / Group 1) | Final u-row syllable shifts to the same column's i-row | 書く → 書き, 飲む → 飲み, 話す → 話し, 立つ → 立ち, 死ぬ → 死に, 遊ぶ → 遊び, 帰る → 帰り |
| Ichidan (一段 / Group 2) | Drop the final る | 食べる → 食べ, 見る → 見, 寝る → 寝, 始める → 始め, 起きる → 起き |
| Irregular する | Stem is し | する → し (勉強し-ます, 勉強し-たい) |
| Irregular 来る | Stem is 来 read き | 来る → 来 (来ます = きます, 来たい = きたい) |
Godan (五段 / Group 1 / u-verbs)
For a godan verb, the final u-row syllable of the dictionary form shifts to the same column's i-row syllable.15 書く (ka-ku) takes the ku → ki shift to give 書き. 飲む (no-mu) takes mu → mi to give 飲み, and 話す (ha-na-su) takes su → shi to give 話し.5 This i-row reflex is why English-language linguistics calls the stem the "i-form."5
毎朝ジョギングをし、シャワーを浴びます。10
"Every morning I go jogging and take a shower."
風が吹き、木が倒れた。2
"The wind blew, and a tree fell."
Ichidan (一段 / Group 2 / ru-verbs)
For an ichidan verb, drop the final る.15 食べる → 食べ, 始める → 始め, 起きる → 起き, 教える → 教え. The shortest stem in the language belongs to 見る → 見, a single mora (rhythmic sound unit).3 The bare 見 stem is rare in isolation but standard before auxiliaries (見ます, 見たい, 見ながら).3
朝早く起き、ニュースを見ます。4
"I get up early in the morning and watch the news."
宿題を終え、友達に電話した。10
"I finished my homework and called a friend."
Irregulars: する and 来る
する takes the stem し, which appears in 勉強します, 勉強したい, and 勉強しながら.5 来る takes the kanji 来 in the stem, but reads it き: 来ます = きます, 来た = きた, 来たい = きたい.11
Wiktionary's conjugation table for 来る lists three readings of the kanji across the paradigm: き in the 連用形, く in the dictionary form, and こ in the 未然形 (来ない).11
The stem of 来る is written 来 but read き in the 連用形 row. 来ます = きます, not くます; 来たい = きたい, not くたい. The く reading belongs to the dictionary form 来る only.11
友達が家に来たいと言っている。11
"My friend says he wants to come over to my house."
毎日練習し、試合に備える。4
"I practice every day and prepare for the match."
The "drop ます" shortcut, and when it misleads
The "drop ます" mnemonic is reliable once the masu-form is in memory: 書きます → 書き; 食べます → 食べ; 来ます (きます) → 来 (き); します → し.4 The shortcut is useful, but it undersells the form in two ways.
First, it hides the underlying i-row pattern that produces the godan stem: a learner who only knows "drop ます" cannot derive 書き from 書く without going through the masu-form on the way.5
Second, the shortcut makes the stem feel polite, because the form the learner is removing ます from is polite. The stem itself is register-neutral; the politeness lives in ます.310 Maggie Sensei states the relationship directly: the stem is what you get by removing ます, but it is not itself the polite form.10
What the masu-stem does
The same stem does three jobs. It is the base for a productive set of suffixes (including ます itself). It is the slot through which Japanese builds compound verbs. It also serves as a noun and as a literary clause-linker on its own. Each job is worth seeing separately.
As the base for polite and derivational endings
The stem is the attachment point for the productive auxiliary inventory.34
| Suffix | Meaning | Example | JLPT |
|---|---|---|---|
| ます | polite present / future | 書きます "write [polite]" | N5 |
| たい | desire ("want to V") | 食べたい "want to eat" | N5 |
| ながら | simultaneous ("while V-ing") | 食べながら "while eating" | N4 |
| やすい | "easy to V" | 読みやすい "easy to read" | N4 |
| にくい | "hard to V" | 読みにくい "hard to read" | N4 |
| すぎる | excess ("V too much") | 食べすぎる "eat too much" | N4 |
| 方 (かた) | "the way of V-ing" | 書き方 "how to write" | N4 |
| なさい | gentle imperative | 食べなさい "eat (please)" | N4 |
| そう | evidential ("looks like it will V") | 降りそう "looks like it'll rain" | N4 |
The honorific frames sit on the same slot. Sonkeigo builds with お + V-stem + になる (お書きになる, "writes [respected]"); kenjōgo builds with お + V-stem + する (お持ちする, "I [humbly] carry").12
日本で働きながら日本語を勉強したいです。4
"I want to study Japanese while working in Japan."
この本はとても読みやすいです。3
"This book is very easy to read."
食べすぎて、お腹が痛い。3
"I ate too much, and my stomach hurts."
先生が教室にお入りになりました。12
"The teacher entered the classroom."
As the base for compound verbs (V1-stem + V2)
NINJAL's 複合動詞レキシコン defines the modern Japanese compound verb as the 動詞連用形＋動詞型 pattern: the first verb stands in its 連用形, and the second verb carries the conjugation of the whole.8 The lexicon catalogues over 2,700 compound verbs in current use. It also observes that Japanese stands out among East Asian languages in both the quantity and the expressive diversity of its compound-verb inventory.8
The same pattern produces 取り出す ("take out"), 飛び込む ("jump into"), 立ち上がる ("stand up"), 食べ過ぎる ("over-eat"), 書き直す ("rewrite"), 読み始める ("start reading"), 押し開ける ("push open"), and 流れ着く ("drift ashore").8 The first verb donates its stem; the second carries tense, aspect, politeness, and negation.
Several V2 positions are open enough to attach to most action verbs and form productive sub-families. These range from the aspectual phase markers (begin, finish, continue) to the ～出す / ～切る / ～込む / ～直す aspect suffixes:8
子どもがプールに飛び込んだ。8
"The child jumped into the pool."
八時に仕事をし始めます。4
"I start work at eight."
書類を書き直し、提出した。8
"I rewrote the documents and submitted them."
As a noun (the stem alone)
The bare stem of a verb is often a noun. 動き ("movement"), 始まり ("a beginning"), 終わり ("an end"), 帰り ("the return trip"), 集まり ("a gathering"), 教え ("a teaching"), and 流れ ("a flow") all read as nouns for the event the verb names.9
The TUFS Tanana write-up frames stem-nominalisation as a "簡便な名詞形成法" (simple noun-formation method) that has been in Japanese 古くからある (since ancient times). It proceeds from event-noun reading outward to argument and adjunct senses by metonymy.9
The pattern is not productive in every case. The reliable picture is three tiers of acceptability.
| Tier | Productivity | Examples | Notes |
|---|---|---|---|
| A | Fully productive event-noun | 動き, 始まり, 終わり, 帰り, 集まり, 教え, 流れ | Action verb yields event-noun; the safest reading9 |
| B | Semi-productive, lexicalised | 飲み (a drinking session), 遊び (play, slack), 救い (salvation), 賭け (a bet), 連れ (a companion) | Real but with narrowed meaning; confirm in a dictionary139 |
| C | Frozen or marginal | 話 (a talk, frozen orthographically), 打ち, 隠れ | Rarely heard standalone; often acceptable only inside compounds (野菜炒め)9 |
Treat stem-derived nouns as vocabulary to confirm in a dictionary, not as a rule to use on demand.139 Even a Tier C marginal stem can become acceptable inside a compound: 野菜炒め ("stir-fried vegetables") is fluent where 炒め on its own is not.9
電車の動きが止まった。13
"The train's movement stopped."
帰りに牛乳を買った。13
"I bought milk on the way home."
今夜飲みに行きませんか。13
"Want to go for drinks tonight?"
As a literary clause-linker (the 中止法 / chūshi-hō reading)
In written Japanese, the stem can replace the te-form between clauses. Bunpro classifies this use as the Formal Conjunctive, used "primarily in written language," with the te-form "heard much more frequently in daily speech."2 The clause break is marked by 読点 (the Japanese comma).2
The propositional content matches the te-form alternative. 雨が降り、風が吹く reads the same as 雨が降って、風が吹く ("It rains and the wind blows"). The stem version is more compact and signals written register.210 Maggie Sensei tags the form as "more literal and formal" and "preferred in business writing and formal speech rather than casual conversation."10
Native-speaker summaries note that 中止法 is rarely heard in spoken Japanese but is natural in written language. It also appears on television when a presenter is reading a news manuscript rather than speaking conversationally.2
This is also the strongest reason to derive the stem from the dictionary form, not from the masu-form. Two of the three productive jobs (stem-as-noun and 中止法) involve a stem that never meets ます at all.12
風が吹き、悪魔が現れた。2
"The wind blew, and a demon appeared."
スピードを出しすぎ、警察に捕まった。2
"I was going too fast and got pulled over by the police."
兄は東京におり、姉は大阪にいます。2
"My older brother lives in Tokyo, and my older sister lives in Osaka."
Nuance and usage contexts
Register: the stem is neutral, ます is the polite part
The stem itself carries no register marker. 食べたい (plain, "want to eat") and 食べます (polite, "eat") share the same stem 食べ, and the politeness of the second sits in ます, not in the stem.3 The formality of 中止法 comes from the construction, not from the stem alone.10
This is why the same stem can sit in casual constructions (食べたい, 食べすぎ) and in formal constructions (お食べになる, 食べ、〜) without changing form.12 The stem is the attachment slot. What gets attached decides the register.
Productivity limits on noun derivation
Tanana notes that not every verb yields an equally productive stem: 炒め from 炒める is real morphologically but rare as a stand-alone noun, even though the compound 野菜炒め is fluent.9 Koizumi's A Dictionary of Basic Japanese Verb Usage lists stem-derived nouns as lexical entries. The implication is that writers should look them up rather than coin them.13
The reliable pattern is the Tier A event-noun reading: most action verbs yield a noun for the event the verb names (動き, 始まり, 終わり, 帰り, 教え, 集まり, 流れ).9 Outside that pattern, the stem is a candidate noun rather than a guaranteed one, and a dictionary check decides.
Why "i-form" is the linguistics-side name
For 五段 verbs, the stem ends in an i-row syllable (書き, 飲み, 話し, 待ち, 遊び). This is why English-language theoretical linguistics labels the slot the "i-form."5 For 一段 verbs there is no -i suffix, and the name is preserved across the paradigm by analogy with the godan reflex.56
Frellesvig's historical account derives the modern 連用形 from the Old Japanese -i nominal / connective stem. That stem did double duty as an event-noun base and clause-linker.6 Both modern jobs (stem-as-noun and 中止法) survive from that single Old Japanese source. The slot has carried its jobs forward without multiplying them.
When the clause-linker stem is appropriate (and when it sounds stilted)
中止法 is appropriate in newspapers, novels, news scripts, formal essays, business writing, and set phrases such as どうぞ、お読みください.210 It is stilted in casual chat, text messages, and friend-to-friend email. The te-form is the everyday connector.210 This is the most common register mistake intermediate learners make once they learn the form.
Maggie Sensei flags one more morphological restriction: avoid 中止法 when the resulting stem is a single mora. A line such as 兄が来、… reads as truncated rather than literary, because the stem 来 (き) is only one mora. The te-form 来て is the right choice instead.10 The same applies to 出 (で), 見 (み), and 寝 (ね).
中止法 with a one-mora stem reads as cut off rather than written-register. 兄が来、… → use 兄が来て、…. The same swap applies for 出, 見, and 寝.10
Good to know
Treating the stem as polite because it "comes from ます"
The stem is register-neutral. The "drop ます" procedure is reliable for finding the form, but it can make the leftover seem polite. It is not. 食べたい (plain) and 食べます (polite) both attach to the same neutral stem 食べ, and the politeness of the second lives in ます.310
Using 中止法 in casual conversation
中止法 reads as written-language register. In chat-message or friend-to-friend prose, it sounds stilted. A learner who writes 友達と話し、帰った in a casual message should use the te-form instead.
友達と話して、帰った。2
"I chatted with my friend and went home."
The te-form is the conversational connector; reserve the stem for newspapers, essays, and business writing.210
Inventing a noun from any verb stem on demand
Stem-nominalisation is lexicalised, not freely productive. A learner who wants to say "yesterday's hit was strong" cannot simply produce 昨日の打ち. 打ち exists morphologically but not as a stand-alone count noun. The native expression uses 一打 or 打撃.
昨日の一打は強かった。13
"Yesterday's hit was strong."
Before deploying a stem as a noun outside the Tier A event-noun pattern, confirm the reading in a dictionary.139
連用形 names a paradigm slot, not a verb-only form
The 連用形 is a slot shared across the inflecting word classes (用言). That is why the name literally says "attaches to 用言," not "attaches to verbs." I-adjectives also have a 連用形, which ends in -く: 高く, 早く. The same morphology that produces 早く起きる ("get up early") sits in the same paradigm slot as 書き or 食べ.16
The Old Japanese -i stem behind the modern form
Frellesvig derives both the noun-deriving job (動き, 帰り) and the clause-linker job (雨が降り、…) from the Old Japanese -i nominal / connective stem.6 The modern 連用形 has not invented new jobs since Old Japanese. It has carried the same two jobs forward, with new auxiliaries (ます, た, たい, ながら) layered onto the same slot.6
Drop the ます, keep the work
A short mnemonic for learners who have memorised the masu-form first: drop the ます, keep the work. The bare stem is what is left over. It is the slot that does the derivation job, the noun job, and the clause-link job. The ます itself contributes politeness, nothing more.10
Writing the 来る stem with the wrong reading
The stem of 来る is written 来 but read き, not く. 来ます is read きます; 来た is read きた; 来たい is read きたい.
明日来ます。11
"I'll come tomorrow."
The same kanji 来 takes three readings across the paradigm: き in the 連用形, く in the dictionary form, and こ in the 未然形 (来ない).11 This is the most common N5-to-N4 reading mistake on this verb.
See also
- Japanese Verb Groups: 一段, 五段, and Irregular
- The Te-Form in Japanese: Construction Rules
- Japanese Adjectives Overview: The Two Classes (い-形容詞 vs な-形容詞)
- Keigo Grammar Overview: How to Conjugate Honorific, Humble, and Polite Verbs
- Parts of Speech in Japanese: The 10 Classes (品詞)
- Classical Grammar Survivals in Modern Japanese