The Short Form: Plain Conjugation for Verbs, Adjectives, and Nouns

Why Short Form Matters More Than You Think

Most textbooks start with polite form (ます/です), and for good reason — it's safe, universally appropriate, and easier to learn. But here's what they sometimes don't tell you early enough:

Short form isn't just "casual Japanese." It's the grammar engine.

Yes, you use short form with friends and family. But you also use it:

• Before と思う (to omou) — "I think that..."
• Before と言う (to iu) — "Someone said that..."
• Before から — "because..."
• Before ので — "because..." (polite)
• Before のに — "even though..."
• Before 時 (toki) — "when..."
• Inside relative clauses — "the person who..."
• Before ことができる — "can do..."
• Before つもり — "plan to..."
• Before でしょう — "probably..."

Every one of these requires the short form, even in polite speech. You can't say ます思う or です時 — the grammar breaks. That's why mastering short form isn't optional. It's the key that unlocks intermediate Japanese.

This post brings together every short form you need — verbs, い-adjectives, な-adjectives, and nouns — in one place.

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Part 1: Verb Short Forms

If you've been following the conjugation series, you've already seen these forms. Here's the complete picture.

Ichidan Verbs (Group 2)

The easiest group. Drop る, add the ending.

Four forms. One stem (食べ / 見). No surprises.

Godan Verbs (Group 1)

Godan verbs shift their final consonant depending on the form. The present negative uses the あ-row, while the past tense has the famous sound changes.

Present Short Forms

Remember: う-ending verbs use わない, not あない. 買う → 買わない.

Past Short Forms (The Sound Changes)

This is the part that trips everyone up. The past tense short form has the same sound changes as the て-form — just replace て/で with た/だ:

Exception: 行く → 行った (not 行いた).

Past Negative

Good news — the past negative is completely regular for all godan verbs. Take the ない form and change ない → なかった:

No sound changes. No exceptions. ない → なかった, every time.

Godan Complete Chart

Irregular Verbs

来る changes its reading in every form: く→こ (ない), く→き (た). Just memorize it.

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Part 2: い-Adjective Short Forms

い-adjectives are refreshingly consistent. Drop the final い and add the ending.

More Examples

The Irregular One: いい (good)

The only い-adjective that breaks the rules. Every form except the present uses the stem よ:

This applies to compounds containing いい, like かっこいい → かっこよかった.

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Part 3: な-Adjective Short Forms

な-adjectives don't change themselves at all. The copula (だ/じゃない/だった/じゃなかった) does the work.

More Examples

Don't Confuse the Types

Remember: きれい and 嫌い (kirai) end in い but are な-adjectives. They follow the だ/じゃない pattern, not the い/くない pattern.

❌ きれくなかった ✅ きれいじゃなかった

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Part 4: Noun Short Forms

Nouns use the same copula pattern as な-adjectives.

Examples:

田中さんは学生だ。— Tanaka is a student. 昨日は雨だった。— Yesterday was rain (it rained). あの人は先生じゃない。— That person isn't a teacher.

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Part 5: Where Short Form Is Actually Used

This is the payoff. Here's how short form plugs into real grammar.

1. Casual Speech

The most obvious use. With friends, family, and people younger than you:

明日どこ行く？ — Where are you going tomorrow? この映画面白かった！ — This movie was interesting! 宿題やってない。 — I haven't done the homework.

2. ～と思う (I think that...)

日本語は面白いと思う。 Nihongo wa omoshiroi to omou. I think Japanese is interesting.

明日雨が降ると思います。 Ashita ame ga furu to omoimasu. I think it will rain tomorrow.

The part before と must be short form. Even in polite speech, you say 降ると思います — not 降りますと思います.

3. ～と言う (to say that...)

先生は明日テストがあると言いました。 Sensei wa ashita tesuto ga aru to iimashita. The teacher said there's a test tomorrow.

Same rule: short form before と. The main verb (言いました) can be polite, but the quoted content stays short.

4. ～から / ～ので (because...)

から (casual/direct):

疲れたから、寝る。 Tsukareta kara, neru. I'm tired, so I'm going to sleep.

ので (softer/polite):

明日テストがあるので、今日勉強します。 Ashita tesuto ga aru node, kyō benkyō shimasu. Because there's a test tomorrow, I'll study today.

With ので, な-adjectives and nouns use な instead of だ:

好きなので (because I like it) — not 好きだので 学生なので (because I'm a student) — not 学生だので

5. Relative Clauses (Describing Nouns with Sentences)

This is one of the most powerful uses. You can turn a whole sentence into a noun modifier:

昨日買った本 — the book I bought yesterday 日本語を話す人 — a person who speaks Japanese 面白くなかった映画 — a movie that wasn't interesting 好きな食べ物 — food that I like

The short form sentence goes directly before the noun. No "that" or "which" needed — Japanese just stacks the clause right in front.

6. ～ことができる (can do...)

日本語を話すことができます。 Nihongo o hanasu koto ga dekimasu. I can speak Japanese.

Short form verb + こと turns a verb into a noun ("the act of speaking"), then ができる means "is possible."

7. ～つもり (plan to...)

来年日本に行くつもりです。 Rainen Nihon ni iku tsumori desu. I plan to go to Japan next year.

買わないつもり。 Kawanai tsumori. I plan not to buy it.

Short form (affirmative or negative) goes before つもり.

8. ～でしょう (probably...)

明日は暑いでしょう。 Ashita wa atsui deshō. It'll probably be hot tomorrow.

もう帰ったでしょう。 Mō kaetta deshō. They probably went home already.

Used for predictions and seeking confirmation.

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The Complete Short Form Cheat Sheet

Verbs

い-Adjectives

な-Adjectives

Nouns

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Short Form vs Polite Form — Side by Side

Notice the pattern: polite form adds ます/です/でした. Short form uses the "raw" conjugation (る/ない/た/なかった for verbs, だ/じゃない/だった for nouns and な-adjectives).

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Common Mistakes to Avoid

1. Using polite form inside grammar patterns

❌ 明日雨が降りますと思います。 ✅ 明日雨が降ると思います。

The part before と思う, から, ので, etc. must be short form. The sentence-final verb can be polite, but the embedded clause cannot.

2. Forgetting だ with な-adjectives and nouns

❌ 学生と思います。 ✅ 学生だと思います。

Before と思う and と言う, nouns and な-adjectives need だ. Without it, the grammar breaks.

But watch out — before ので, you use な instead of だ:

❌ 好きだので / ❌ 学生だので ✅ 好きなので / ✅ 学生なので

3. Mixing up past negative forms

❌ 食べませんかった (mixing polite + plain) ✅ 食べなかった (short) or 食べませんでした (polite)

Pick one register and stick with it. Don't hybridize.

4. Over-dropping だ in casual speech

In casual speech, だ is often dropped after な-adjectives and nouns:

元気？ — Are you well? (not 元気だ？) 学生？ — Are you a student?

But before grammar patterns, you still need it:

元気だと思う ✅ 元気と思う ❌

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A Note on Register

Short form isn't "rude." It's intimate. Japanese speakers constantly switch between polite and short form depending on:

• Who they're talking to (boss → polite, friend → short)
• Where they are (meeting → polite, izakaya → short)
• How long they've known someone (new coworker → polite, same coworker after months → gradually more short form)

Most relationships in Japan naturally migrate from polite to short form over time. Using short form too early feels presumptuous. Using polite form forever feels distant. Finding the right moment to shift is a social skill that native speakers navigate instinctively.

As a learner, you should understand short form from the start (you'll hear it everywhere — anime, music, casual conversation), but use polite form as your default until the other person signals that casual is okay.

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How to Practice

1. Convert polite to short: Take any sentence in ます/です form and convert it. 食べました → 食べた. 面白かったです → 面白かった. 静かでした → 静かだった.
2. Build と思う sentences: Pick any opinion and frame it with と思う. 日本語は楽しいと思う. この店は高いと思う. 明日は晴れだと思う.
3. Practice relative clauses: Describe things using short form + noun. 昨日見た映画, 日本で買った本, 好きな歌手, 元気じゃなかった友達.
4. Diary in short form: Write about your day using only short form. This is how real Japanese diaries are written.
5. Listen for it: In any Japanese media, notice which form characters use and when. The switch between polite and short form tells you a lot about the relationship between characters.

Short form is where textbook Japanese becomes real Japanese. It's the difference between reading a phrasebook and actually understanding what people say. Once you have it down, every grammar pattern that follows becomes easier — because they all build on this foundation.

普通形をマスターしましょう！ (Futsūkei o masutā shimashō!) — Let's master the plain form!