해체 / 반말: The Intimate Style (-아/어)

There is a register of Korean so easy to build that you already know it, and so easy to misuse that it can end a friendship before it starts. It is 해체, the intimate plain style, which everyone calls 반말 ("half-speech"). The forming rule is almost insultingly simple: take the 해요체 form and drop the 요. 가요 → 가. 먹어요 → 먹어. 마셔요 → 마셔. 해요 → 해. That's the entire mechanism. This page teaches how 반말 is formed and where it lives; its companion page on when 반말 is licensed teaches the far harder question of when you're allowed to use it — because the gap between "can form" and "may use" is where learners get into trouble.

Every example on this page is in 반말 on purpose — that is the register being taught. Use these forms only with people who have licensed them; with anyone else, keep the 요.

Forming 해체: strip the 요

Because 반말 is 해요체 with the 요 removed, everything you already learned about the 해요체 form transfers unchanged — the vowel harmony, and all the vowel contractions. You are not learning a new conjugation; you are learning a subtraction.

Because the mood-by-intonation property of 해요체 carries over too, a bare 가 is — just like 가요 — a statement, a question, or a command depending on tone. 가? (rising) is "are you going?"; 가 (falling) is "I'm going"; 가 (to someone, gesturing) is "go."

The copula in 반말: 이야 / 야

The one place 반말 is not simply "해요체 minus 요" is the copula. Where 해요체 has 이에요/예요, 반말 uses 이야 after a consonant and 야 after a vowel.

Notice 뭐야 and 이거 내 거야: the copula question 뭐야? ("what is it?") and the plain 거야 ("it's [mine]") are among the highest-frequency 반말 forms in the language — you will hear them constantly in any casual conversation or K-drama.

Tense and the other endings strip too

The subtraction is general: past, future, and the promise/volition endings all lose their 요 the same way.

Where 반말 lives

반말 is the register of closeness and of downward age. It is used:

• between close friends who have agreed to drop the formalities;
• from an older speaker to a clearly younger one, once the age gap is acknowledged;
• within a family to juniors (an older sibling to a younger, a parent to a child, an aunt to a niece);
• to children generally;
• between romantic partners;
• and in inner speech — thinking, muttering, talking to yourself.

Easy to form, dangerous to deploy

Here is the whole tension of this register in one line: 반말 is trivial to build and treacherous to use. The subtraction that makes it easy — just drop the 요 — is exactly what makes it dangerous, because that dropped 요 was carrying all the deference. Removing it with the wrong person doesn't read as "casual and friendly"; it reads as "I have decided we are close enough that I can talk down to you," which is a claim you may not be entitled to make.

The trap: you cannot make 반말 from 합니다체

A specific and very common error: learners reason "반말 is the polite form minus its politeness marker, so I'll take 합니다 and strip its ending." But 합니다체 does not end in 요 — there is no 요 to drop — and it has no direct 반말 partner. Its plain counterpart is a different level, the written-neutral 한다체 (간다, 먹는다), not 반말 at all. 반말 is specifically the partner of 해요체. So the subtraction only works one way: 해요체 → 반말 (가요 → 가), never 합니다체 → anything (갑니다 has no casual form you can reach by stripping).

Real 반말 borrows 한다체 for its moods

One more truth that textbooks flatten: in the strict grammatical sense, 해체 is only the -아/어 ending (statement/question/command by intonation). But spoken 반말 in the wild is a blend. For the non-statement moods, casual speech routinely reaches over into the plain 한다체 and borrows its dedicated forms — because they are punchier and unambiguous:

• Proposal "let's": 한다체 -자 → 가자, 먹자.
• Emphatic command: 한다체 -아/어라 → 가라, 먹어라.
• Blunt question: 한다체 -냐/니 → 가냐?, 뭐 하니?

So "speaking 반말" in practice means drawing endings from both the intimate 해체 and the plain 한다체 — a mix that the dedicated 반말 moods page untangles ending by ending. The bare -아/어 does statements and gentle questions; 한다체 supplies the strong "let's," the strong "do it," and the blunt "huh?"

Common Mistakes

1. Trying to derive 반말 from 합니다체. 갑니다 has no 요 to drop; strip nothing and you're stuck. 반말 comes only from 해요체 (가요 → 가); the plain partner of 합니다체 is the separate 한다체 (간다).

2. Using the polite copula 이에요/예요 in 반말. The intimate copula is 이야/야, not the 요-marked polite forms.

3. Half-dropping the 요 — inconsistent register. Sliding between 가요 and 가 in the same breath signals you can't tell where you stand with the person. Pick a register and hold it.

4. Assuming 반말 = only the -아/어 forms. In real speech, "let's" and strong commands come from 한다체 (가자, 먹어라), not from bare -아/어. Learning only 해체 leaves you unable to say a natural casual "let's go."

Key Takeaways

• 해체 = 반말 = 해요체 minus 요: 가요 → 가, 먹어요 → 먹어, 해요 → 해. All harmony and contraction rules carry over unchanged.
• The exception is the copula: 반말 uses 이야 (after a consonant) / 야 (after a vowel) — 학생이야, 친구야, 뭐야?
• 반말 lives among close friends, downward in age, family juniors, children, partners, and inner speech — it marks closeness or seniority, never mere friendliness.
• You cannot derive 반말 from 합니다체 (no 요 to drop); it is specifically the partner of 해요체. 합니다체's plain counterpart is the separate 한다체.
• Real spoken 반말 blends in 한다체 moods — 가자 (let's), 먹어라 (do it), 가냐? (blunt question) — so the intimate style in practice draws from two levels at once.