Probability Adverbs: 아마 / 틀림없이 / 설마 (and their endings) | Korean Grammar

English packs certainty into the verb: he *might come, he **must be home, *surely he didn't leave. Korean does it differently — it plants a probability adverb at the front of the clause (아마, 틀림없이, 혹시, 설마) and finishes the sentence with an ending that carries the same degree of certainty. The two are a matched pair. The adverb announces the modality; the ending has to deliver it. This is the single most important thing to learn here: an 아마 with a flat, factual ending sounds broken to a native ear, the way English "probably he comes" sounds wrong to yours.

The certainty ladder

Adverb	Certainty	Clause type it demands
설마	disbelief — "surely not / no way"	question or negative / rhetorical
혹시	tentative — "by any chance"	a question
아마 (아마도)	likely — "probably / perhaps"	conjectural -(으)ㄹ 거예요 / -겠-
분명히 / 틀림없이	near-certain — "surely / definitely"	firm assertion or -(으)ㄹ 거예요

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Think of a probability adverb as a promise about how the sentence will end. 아마 promises a conjecture, so it needs a conjectural ending. 혹시 promises a question. 설마 promises incredulity. Plant the adverb and you have committed to the ending — that agreement is the whole grammar of this group.

아마 (probably) — needs a conjectural ending

아마 means "probably / most likely", and it all but requires the conjectural -(으)ㄹ 거예요 or the modal -겠-. A bare present-tense fact after 아마 — ×아마 와요 ("probably comes") — is exactly the sentence a learner writes and a native never says, because 와요 states a plain fact while 아마 is hedging a guess. Let the ending do the hedging too.

그 사람은 아마 학생일 거예요.

geu sarameun ama haksaeng-il geoyeyo

That person is probably a student.

지금 출발하면 아마 늦을 거예요.

jigeum chulbalhamyeon ama neujeul geoyeyo

If we leave now, we'll probably be late.

내일은 아마 비가 올 거예요.

naeireun ama biga ol geoyeyo

It'll probably rain tomorrow.

The emphatic variant 아마도 ("perhaps, quite possibly") works the same way and just adds a touch of weight or hesitation:

아마도 그때쯤엔 다 끝나 있을 거예요.

amado geuttaejjeumen da kkeunna isseul geoyeyo

Perhaps it'll all be finished by around then.

분명히 / 틀림없이 (surely) — a confident assertion

Higher up the ladder, 분명히 ("clearly, surely") and 틀림없이 (literally "without error" → "certainly") pair with a firm statement or a confident -(으)ㄹ 거예요. Here the ending is allowed to be strong, because the adverb is claiming near-certainty rather than hedging.

틀림없이 시험에 붙을 거예요.

teullimeopsi siheome buteul geoyeyo

You'll definitely pass the exam.

이건 분명히 그 사람 글씨예요.

igeon bunmyeonghi geu saram geulssiyeyo

This is clearly that person's handwriting.

Note the difference from 아마: 틀림없이 can sit in front of a flat assertion (그 사람 글씨예요) because it is asserting, not guessing. Swap in 아마 there and it clashes — a guess cannot be stated as bald fact.

혹시 (by any chance) — pairs with a question

혹시 softens a question, flagging that you are tentatively floating a possibility: "by any chance…?", "you wouldn't happen to…?". It is the politeness workhorse for cautious inquiries and hesitant requests. Its natural home is a question ending; using it in a statement leaves it dangling.

혹시 김 선생님이세요?

hoksi Kim seonsaengnimiseyo

Are you Mr. Kim, by any chance?

혹시 시간 있어요?

hoksi sigan isseoyo

Do you happen to have a minute?

혹시 이 근처에 약국 있어요?

hoksi i geuncheoe yakguk isseoyo

Is there a pharmacy near here, by any chance?

설마 (surely not) — incredulity, not "maybe"

설마 is the trap. Learners meet it glossed as "maybe" and use it for neutral possibility — but 설마 is incredulous: "surely not…", "don't tell me…", "you can't mean…". It expresses that you find something hard to believe and half-hope it isn't true. It leans toward a negative or rhetorical completion, very often the fixed 설마 …-(으)ㄹ 리가 없다 ("there's no way…").

설마 벌써 갔어요?

seolma beolsseo gasseoyo

Don't tell me they already left?

설마 그럴 리가 없어요.

seolma geureol riga eopseoyo

Surely that can't be.

설마 저 사람이 범인일까요?

seolma jeo sarami beomin-ilkkayo

Surely that person isn't the culprit… is he?

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설마 ≠ "maybe". 아마 is the neutral "probably"; 설마 is "no way / you're kidding". If you mean an even, unemotional guess, you want 아마 + a conjectural ending. Reserve 설마 for the moment you are startled and hoping the answer is no.

Why the pairing matters

In English the modal is the verb, so you only make one choice. Korean spreads the modality across two slots — a fronted adverb and a clause-final ending — and both must agree. That means a probability adverb is never a standalone flourish you can drop in and forget: it sets up an obligation at the end of the sentence. See the wider principle of adverb–ending agreement, which recurs across every modal adverb, and the fuller certainty spectrum of endings these adverbs latch onto.

Common Mistakes

1. 아마 with a plain present-tense fact and no conjectural ending. The ending has to hedge too.

❌ 아마 그 사람 집에 있어요.

Wrong — 아마 needs a conjecture: 아마 집에 있을 거예요.

✅ 그 사람 아마 집에 있을 거예요.

geu saram ama jibe isseul geoyeyo

They're probably at home.

2. Reading 설마 as neutral "maybe". It carries disbelief, not even odds.

❌ 설마 내일 올 거예요.

Off — 설마 isn't 'probably'; for a plain guess use 아마 내일 올 거예요.

✅ 아마 내일 올 거예요.

ama naeil ol geoyeyo

They'll probably come tomorrow.

3. Putting 혹시 in front of a statement instead of a question. 혹시 wants a question to complete it.

❌ 혹시 화장실이 저기 있어요.

Odd as a statement — 혹시 flags an inquiry: 혹시 화장실이 어디예요?

✅ 혹시 화장실이 어디예요?

hoksi hwajangsiri eodiyeyo

Where's the restroom, by any chance?

4. 틀림없이 with a hedge, or 아마 with a bald assertion. Match the strength of the ending to the adverb.

❌ 아마 이건 그 사람 글씨예요.

Clash — a guess stated as fact; for certainty use 분명히, for a guess use 아마 … -ㄹ 거예요.

✅ 이건 분명히 그 사람 글씨예요.

igeon bunmyeonghi geu saram geulssiyeyo

This is definitely that person's handwriting.

Key Takeaways

Probability adverbs come in a ladder: 설마 (disbelief) < 혹시 (tentative) < 아마 (likely) < 분명히 / 틀림없이 (near-certain).
Each co-selects an ending: 아마 → conjectural -(으)ㄹ 거예요 / -겠-; 혹시 → a question; 설마 → negative/rhetorical; 틀림없이 → a confident assertion.
아마 is not decoration — a bare factual ending after it sounds broken. Let the ending hedge.
설마 means "surely not", not "maybe" — it is emotional disbelief, most often 설마 …-(으)ㄹ 리가 없다.

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