Plain and Dictionary Forms in Japanese

In Brief

Japanese verbs have four basic plain forms: 食べる “eat/will eat,” 食べない “do not/will not eat,” 食べた “ate,” and 食べなかった “did not eat.” The dictionary form is only the non-past affirmative member of this set—食べる—although learners sometimes use “dictionary form” loosely for plain speech as a whole. Plain forms are used not only with friends, but also inside many otherwise polite sentences.

Overview

The plain form, 普通形（ふつうけい）, is the basic style of a Japanese predicate. A predicate is the part of a sentence that says what happens or what something is; here, the focus is on verbs. Unlike the polite ます style, plain verbs do not end in ます, ません, ました, or ませんでした. They instead use endings such as る, ない, and た.

At A2, the simplest use is casual conversation: 明日、何する？ means “What are you doing tomorrow?” But “plain” does not simply mean “slang” or “impolite.” These forms also appear before grammar expressions, inside quotations, and in clauses that describe a noun—even when the sentence ends politely. For example, 昨日買った本です (“It is the book I bought yesterday”) contains plain 買った inside a polite sentence.

English often marks time with separate verb forms and may add “do” for negatives and questions. Japanese changes the verb ending instead. It also has one combined non-past form for both present and future meanings: 行く can mean “go,” “goes,” or “will go,” depending on context.

How It Works

The four-form framework

Start by learning every verb as a set of four. “Non-past” means a form that can refer to the present, habitual actions, or the future.

Meaning	Plain ending	食べる “eat”	行く “go”	Polite counterpart
Non-past affirmative	Dictionary form	食べる	行く	食べます / 行きます
Non-past negative	ない-form	食べない	行かない	食べません / 行きません
Past affirmative	た-form	食べた	行った	食べました / 行きました
Past negative	なかった-form	食べなかった	行かなかった	食べませんでした / 行きませんでした

Japanese does not change the verb for grammatical person. 食べる can follow “I,” “you,” “she,” or “they”; the subject is understood from context or stated with a noun or pronoun.

Dictionary form: the non-past affirmative

The dictionary form is the form used as a dictionary headword: 食べる, 書く, 話す, する. For an affirmative action verb, its exact time comes from context:

• 毎日走る。 — “I run every day.”
• 明日走る。 — “I will run tomorrow.”

Do not add a separate future ending. Japanese has no general verb tense corresponding exactly to English “will.”

Verb groups

Formation depends on the verb group.

Group 2: ichidan verbs

Many verbs ending in -いる or -える are Group 2, also called ichidan (“one-step”) verbs. Remove final る and add the required ending.

Dictionary	Stem	Negative	Past	Past negative
食べる	食べ-	食べない	食べた	食べなかった
見る	見-	見ない	見た	見なかった
起きる	起き-	起きない	起きた	起きなかった

The -いる/-える clue is useful, not absolute. Common exceptions such as 入る (“enter”), 走る (“run”), 帰る (“return”), and 切る (“cut”) are Group 1.

Group 1: godan verbs

Group 1, or godan (“five-step”), verbs change their final kana. To make the negative, move the final u-row sound to its a-row partner and add ない. A final う changes to わ, not あ.

Dictionary	Negative	Past	Past negative
書く	書かない	書いた	書かなかった
話す	話さない	話した	話さなかった
待つ	待たない	待った	待たなかった
読む	読まない	読んだ	読まなかった
遊ぶ	遊ばない	遊んだ	遊ばなかった
死ぬ	死なない	死んだ	死ななかった
取る	取らない	取った	取らなかった
買う	買わない	買った	買わなかった
泳ぐ	泳がない	泳いだ	泳がなかった

The plain past uses the same sound changes as the て-form, with た/だ replacing て/で:

Dictionary ending	Plain past ending	Example
う・つ・る	った	買う → 買った
む・ぶ・ぬ	んだ	読む → 読んだ
く	いた	書く → 書いた
ぐ	いだ	泳ぐ → 泳いだ
す	した	話す → 話した

One important exception is 行く → 行った, not ×行いた.

Irregular verbs

Dictionary	Negative	Past	Past negative
する “do”	しない	した	しなかった
来る（くる） “come”	来ない（こない）	来た（きた）	来なかった（こなかった）
ある “exist; have”	ない	あった	なかった

Compounds follow する: 勉強する → 勉強しない → 勉強した → 勉強しなかった.

Turning polite forms into plain forms

Do not normally remove ます and stop there. The piece before ます is a verb stem, not necessarily a complete plain form:

Polite	Plain	Not this
食べます	食べる	×食べ
書きません	書かない	×書きない
行きました	行った	×行きた
読みませんでした	読まなかった	×読みないでした

It is more reliable to identify the dictionary form and verb group, then build the correct plain ending.

Questions and sentence endings

In casual speech, intonation often turns a plain statement into a question, with no か:

• 明日、何する？ — “What are you doing tomorrow?”
• これ、知ってる？ — “Do you know this?”

Sentence-final の？ can ask for an explanation or show personal interest: どうして行かないの？ (“Why aren’t you going?”). Casual questions with plain か also exist, but they may sound firm, masculine, literary, or like self-questioning depending on context. Beginners should not simply replace polite ですか／ますか with plain か in every conversation.

Examples in Context

Japanese	English	Note
毎朝、コーヒーを飲む。	I drink coffee every morning.	Habitual non-past
週末は家にいる。	I’ll be at home this weekend.	Future meaning from context
肉は食べない。	I don’t eat meat.	Plain negative
昨日、駅まで歩いた。	I walked to the station yesterday.	Plain past
朝ご飯を食べなかった。	I didn’t eat breakfast.	Plain past negative
明日、何する？	What are you doing tomorrow?	Casual question
これ、知ってる？	Do you know this?	Spoken contraction of 知っている
田中さんは来ないと思います。	I think Tanaka won’t come.	Plain form before と思います
日本へ行ったことがあります。	I have been to Japan.	Plain past before ことがある
漢字を読むことができる。	I can read kanji.	Dictionary form before ことができる
母が作ったケーキです。	It is a cake my mother made.	Plain clause describing ケーキ
寝る前に、歯を磨きます。	I brush my teeth before going to bed.	Plain form inside a polite sentence
時間がないから、急ごう。	We don’t have time, so let’s hurry.	Plain reason clause
雨が降るそうです。	I hear that it will rain.	Plain form before hearsay そうです

Common Mistakes

Treating “dictionary form” and “plain form” as exact synonyms

• Wrong idea: Every plain form is a dictionary form.
• Right: 食べる is both dictionary and plain; 食べない, 食べた, and 食べなかった are plain but not dictionary forms.
• Why: “Plain form” names a style and a four-way set. “Dictionary form” names the non-past affirmative form listed in dictionaries.

Removing ます mechanically

• Wrong: ×昨日、映画を見たつもり formed as ×見ました → 見まし
• Right: 昨日、映画を見た。
• Why: Return to 見る, identify it as Group 2, and form 見た. The polite ending is not converted by merely chopping off letters.

Using Group 2 rules on a Group 1 verb

• Wrong: ×明日、家に帰ない。
• Right: 明日、家に帰らない。
• Why: Although 帰る ends in -える, it is Group 1: る → らない.

Making the past of 行く by the regular く pattern

• Wrong: ×京都へ行いた。
• Right: 京都へ行った。
• Why: 行く is the major exception to the く → いた past pattern.

Using casual style with the wrong person

• Wrong for a formal situation: 先生、明日来る？
• Right: 先生、明日来ますか。
• Why: A plain sentence ending can sound too familiar when addressing a teacher, customer, stranger, or senior. The relationship matters more than the grammar’s difficulty.

Avoiding plain forms inside polite sentences

• Wrong: ×昨日買いました本です。
• Right: 昨日買った本です。
• Why: A clause directly describing a noun normally uses plain form. Politeness is usually marked at the end of the whole sentence.

Usage Notes

Plain style is natural among family, close friends, children, and peers who have established an informal relationship. It is also common in diaries, notes, headlines, fiction, and explanatory writing. That does not make every plain sentence equally casual: written Japanese may use plain forms in an objective, formal-sounding prose style.

Japanese politeness is not a word-for-word switch. A speaker may use plain forms with a friend but choose polite forms when creating distance, showing care, or changing the tone. Conversely, suddenly switching to plain speech with someone senior can sound presumptuous. When uncertain, use です／ます at the end of your own sentences.

Within a complex sentence, style can mix for grammatical reasons. 明日行くと思います is polite overall because it ends in 思います, while 行く before the quotation particle と is plain. English speakers often try to make every verb polite once a sentence is polite; Japanese generally places the main politeness marker at the end.

In conversation, ている commonly contracts to てる: 知っている？ → 知ってる？, 何をしているの？ → 何してるの？. This is normal casual speech, but the uncontracted form is clearer in careful writing and in early study.

Beyond the Basics: Plain Forms Are Not Only Verbs

You do not need to master all of this at A2, but later grammar books use “plain form” for entire predicates, including い-adjectives, な-adjectives, and nouns.

Predicate type	Non-past affirmative	Non-past negative	Past affirmative	Past negative
Verb	行く	行かない	行った	行かなかった
い-adjective	高い	高くない	高かった	高くなかった
な-adjective	静かだ	静かではない	静かだった	静かではなかった
Noun	学生だ	学生ではない	学生だった	学生ではなかった

The linking word だ belongs to plain noun and な-adjective predicates, but it does not follow a verb: 行く, not ×行くだ. Also, some grammar patterns omit だ even where a table suggests it—for example, 学生だと思う uses it, while 学生のとき uses の before とき. Learn the connection required by each pattern rather than inserting だ automatically.

Plain forms also do several jobs that are not casual:

• Relative clauses (clauses describing a noun): 日本で撮った写真 — “a photo taken in Japan.”
• Quotations and thoughts: 行かないと言いました — “She said she would not go.”
• Nominalization (turning an action into a noun-like unit): 料理することが好きです — “I like cooking.”
• Time and condition patterns: 寝るとき, “when going to bed”; 着いたら, “when/if [someone] arrives.”

A further stylistic distinction appears in formal writing. Japanese expository prose often ends sentences in the plain だ／である style rather than です／ます. This style can sound authoritative and impersonal, not friendly or casual. It is best recognized first and imitated only when you understand the genre.

Practice Tips

1. Learn verbs in four-part chains. Say 書く・書かない・書いた・書かなかった aloud rather than memorizing each form separately. Mix Group 1, Group 2, and irregular verbs.
2. Transform useful sentences, not isolated endings. Change 今日は働きます into 今日は働く, then make it negative and past. This connects form, meaning, and register.
3. Listen for embedded plain forms. In polite audio, pause at phrases such as と思います, ことができます, and noun descriptions. Mark the plain verb before the polite ending; this prevents the mistaken idea that plain forms belong only to casual conversations.

Related Concepts

• Prerequisite: Polite Form ます — compare the four polite endings with their plain equivalents.
• Next step: ない-Form (Negative Plain) — practise Group 1, Group 2, and irregular negative formation in depth.
• Next step: Relative Clauses — use plain clauses directly before nouns.
• Next step: Quotation Particle と — report speech and thoughts with plain forms.
• Next step: Ability ことができる — attach ことができる to the dictionary form.
• Next step: とき (when) — see how tense and affirmation affect clauses before とき.
• Next step: Hearsay そうです — report information with a plain clause before そうです.
• Later study: Potential Form — express ability with a dedicated verb form.