Nominalization -기 and -(으)ㅁ in Korean

In Brief

Korean can turn a verb or adjective into a noun-like expression by adding -기 or -(으)ㅁ. -기 commonly presents an action or process—읽기 “reading”—whereas -(으)ㅁ often packages a fact, state, or result—왔음 “the fact that someone came”—and is especially common in formal writing. In everyday conversation, -기 and -는 것/거 are generally more frequent than -(으)ㅁ.

Overview

Nominalization means making an action, event, or quality behave like a noun (a word or phrase treated as a “thing”). English often does this with an -ing form or a clause beginning with “the fact that”: “Reading is useful,” “I like swimming,” or “I knew that he had arrived.” Korean does not rely on one equivalent for all of these. It chooses among forms such as -기, -(으)ㅁ, and -는 것 according to meaning, construction, and register.

This B2 topic matters because nominalized expressions can fill several positions in a sentence. They may be a subject, an object, or part of a larger pattern: 한국어 배우기가 재미있어요 “Learning Korean is fun,” 수영하기를 좋아해요 “I like swimming,” and 그가 왔음을 알았어요 “I knew that he came.” A particle—a short marker showing a phrase’s role—can follow the entire nominalized unit.

The broad contrast is useful but not absolute: -기 tends to focus on doing or experiencing an action, while -(으)ㅁ tends to present information as an established fact, condition, result, record, or abstract quality. Many verbs also select one form as part of a conventional pattern, so natural usage cannot always be predicted from the English translation alone.

How It Works

Forming -기

Attach -기 directly to the verb or adjective stem. The stem is the form left after removing -다 from the dictionary form.

Dictionary form	Stem	Nominalized form	Basic sense
읽다	읽-	읽기	reading; to read as an activity
쓰다	쓰-	쓰기	writing
듣다	듣-	듣기	listening
말하다	말하-	말하기	speaking
배우다	배우-	배우기	learning
쉽다	쉽-	쉽기	being easy

The ending does not change according to the final sound of the stem. Many familiar expressions are built around it:

• -기 쉽다/어렵다: to be easy/difficult to do
• -기 좋다: to be good for doing
• -기 시작하다: to begin doing
• -기를 좋아하다/싫어하다: to like/dislike doing
• -기로 하다: to decide or agree to do
• -기 위해(서): in order to do
• -기 때문에: because
• -기 바라다: to hope that; used often in notices and polite writing

In 배우기 쉬워요, the nominalized verb 배우기 is followed directly by 쉽다. English says “easy to learn,” but Korean builds the expression as “learning is easy.” Do not add a particle unless the particular construction needs one.

Forming -(으)ㅁ

Choose -음 after most consonant-final stems and -ㅁ after vowel-final stems. A stem ending in ㄹ keeps that ㄹ and combines it with ㅁ in the same syllable.

Stem ending	Dictionary form	Nominalized form	Basic sense
consonant	먹다	먹음	eating; the fact of eating
consonant	있다	있음	existence; being present
vowel	가다	감	going; the fact that one goes
vowel	하다	함	doing; the fact that one does
ㄹ	만들다	만듦	making; the fact that one makes
ㄹ	알다	앎	knowing; knowledge
adjective	아름답다	아름다움	beauty; being beautiful

The compact spellings 감, 함, 앎, and 만듦 can surprise learners. They are not shortened informal forms: they are the regular written results of adding -ㅁ. In particular, write 만듦, not 만듬.

Adding tense and negation

Tense or aspect can appear before the nominalizer when the time distinction matters:

Meaning	-기 form	-(으)ㅁ form
go / going	가기	감
went / having gone	갔기	갔음
will go / intended future	갈 것이기, 가게 될 것이기	갈 것임
not go	가지 않기	가지 않음

Past -았/었- combines naturally with both forms, but -(으)ㅁ is especially common when recording or recognizing a completed fact: 그가 이미 떠났음을 확인했다 “I confirmed that he had already left.” Future meaning is usually expressed with -(으)ㄹ 것 plus the copula rather than by attaching a special future ending directly: 변경될 것임을 알려 드립니다 “We inform you that it will be changed.”

Giving the nominalized phrase a role

Once nominalized, the expression can take particles much like a noun. In speech, particles are sometimes omitted when the meaning is clear.

Role	Pattern	Example
subject/topic	-기 + 가/는	걷기가 좋아요.
object	-기 + 를	책 읽기를 좋아해요.
object, formal fact	-(으)ㅁ + 을/를	사실이 아님을 밝혔다.
recognition/existence	-(으)ㅁ + 이/가	차이가 있음이 분명하다.

Korean frequently places a subject inside the nominalized clause. Compare 오기가 어렵다 “coming is difficult” with 민수가 오기가 어렵다 “it is difficult for Minsu to come.” With fact-like -(으)ㅁ, a written subject marker is common: 그가 왔음을 알았다 “I knew that he came.”

Choosing between -기, -(으)ㅁ, and -는 것

Korean pattern	English	Typical focus
운동하기	exercising	the activity or act of doing
운동하는 것	exercising; the thing one does	neutral, concrete description; very common in speech
운동함	the fact/state of exercising	factual, abstract, concise, or written

-는 것 is often the safest neutral choice in conversation. It uses a noun-modifying form—the form that places a description before a noun—plus 것 “thing.” In casual speech, 것 commonly becomes 거: 요리하는 거 좋아해요? “Do you like cooking?” By contrast, 요리함을 좋아해요 sounds unnecessarily formal and unnatural for an everyday preference.

The noun or expression after the clause also affects the choice. Korean normally says 잊지 않기 위해 “in order not to forget” and 내일 만나기로 했어요 “we decided to meet tomorrow.” Replacing -기 with -(으)ㅁ in these fixed constructions is not merely a change in style; it breaks the pattern.

Examples in Context

Korean	English	Note
읽기, 쓰기, 듣기, 말하기를 매일 연습해요.	I practice reading, writing, listening, and speaking every day.	Activities named with -기
수영하기를 좋아해요.	I like swimming.	-기를 좋아하다
이 설명은 이해하기 쉬워요.	This explanation is easy to understand.	-기 쉽다
비가 오기 시작했어요.	It started to rain.	-기 시작하다
건강을 위해 매일 걷기로 했어요.	I decided to walk every day for my health.	-기로 하다
늦지 않기 위해 일찍 출발했어요.	I left early in order not to be late.	Negation before -기
한국에서 혼자 살기가 처음에는 힘들었어요.	Living alone in Korea was difficult at first.	Entire phrase marked with 가
그가 왔음을 알았어요.	I knew that he had come.	A recognized fact
두 자료의 내용이 다름을 확인했습니다.	We confirmed that the contents of the two documents differ.	Formal written report
신청 기간이 끝났음을 알려 드립니다.	We inform you that the application period has ended.	Formal notice
회의실에 빈자리가 없음을 확인했다.	I confirmed that there were no empty seats in the meeting room.	State or absence
이 작품의 아름다움은 색채에 있어요.	The beauty of this work lies in its colors.	Lexicalized abstract noun
준비물: 신분증. 수수료 없음.	Required item: ID. No fee.	Concise notice style
문이 잠겨 있음을 꼭 확인하세요.	Make sure that the door is locked.	Fact/state embedded under 확인하다

Common Mistakes

Treating -기 and -(으)ㅁ as freely interchangeable

• Unnatural: 내일 만나음으로 했어요.
• Right: 내일 만나기로 했어요.
• Why: -기로 하다 is the established pattern for making a decision or agreement. Learn common constructions as complete units rather than swapping nominalizers word by word.

Using -(으)ㅁ for an ordinary spoken preference

• Unnatural in conversation: 저는 수영함을 좋아해요.
• Natural: 저는 수영하기를 좋아해요. / 저는 수영하는 걸 좋아해요.
• Why: A hobby is normally framed as an activity with -기 or conversational -는 것/거. -(으)ㅁ makes this sentence sound stiff and document-like.

Choosing -음 after a vowel

• Wrong: 가음, 하음
• Right: 감, 함
• Why: Add -ㅁ after a vowel-final stem. The ㅁ becomes the final consonant of the preceding syllable.

Dropping ㄹ before -ㅁ

• Wrong: 만듬, 아음
• Right: 만듦, 앎
• Why: A stem-final ㄹ remains before ㅁ. The resulting final consonant cluster is written ㄻ.

Translating every English “-ing” form with -기

• Unnatural: 길을 걷기 사람 for “the person walking down the street”
• Right: 길을 걷는 사람
• Why: English -ing has several jobs. Before a noun, Korean normally needs a noun-modifying form such as -는, not nominalization. -기 makes the action noun-like; it does not directly describe 사람.

Adding a particle where the construction does not take one

• Wrong: 배우기가 쉬워요 in every context is not wrong, but 배우기를 쉬워요 is.
• Right: 배우기 쉬워요. / 한국어는 배우기가 쉬워요.
• Why: In -기 쉽다, no object particle follows -기. Subject -가 may appear when the nominalized activity itself is explicitly presented as the subject.

Usage Notes

In conversation, -기 is productive and natural, particularly in fixed patterns. It also labels skills, categories, or tasks: 읽기 “reading,” 말하기 시험 “speaking test,” and 즐겨찾기 “favorites/bookmarking.” When speakers simply talk about an action as a concrete experience, however, -는 것/거 often sounds more conversational: 여행하는 걸 좋아해요 is at least as natural as 여행하기를 좋아해요.

-(으)ㅁ is prominent in reports, announcements, contracts, academic prose, application screens, lists, and short notes. Forms such as 해당 없음 “not applicable,” 이상 없음 “no abnormalities/problems,” and 사용 가능함 “available for use” are concise and impersonal. This style can end an item with -(으)ㅁ without a following particle. It resembles a label, record, or memo rather than ordinary polite conversation.

Some -(으)ㅁ forms have become established nouns whose meanings may be broader than a freshly nominalized clause: 삶 “life,” 죽음 “death,” 꿈 “dream,” 믿음 “belief/faith,” 도움 “help,” and 아름다움 “beauty.” Treat common lexicalized forms as vocabulary. Their spelling or meaning may not be fully predictable just by applying a classroom formula.

English can hide an important distinction because both forms may be translated with -ing. Ask what the Korean sentence is doing: naming an activity, embedding a known fact, or describing a concrete act with 것? That question is more reliable than matching endings mechanically.

Beyond the Basics

Nominalized facts inside formal clauses

-(으)ㅁ often occurs before verbs of knowing, realizing, confirming, proving, announcing, or remembering. The following particle is frequently -을/를:

• 문제가 있음을 인정했다. — “They acknowledged that there was a problem.”
• 결과가 정확함을 증명했다. — “They proved that the result was accurate.”
• 일정이 변경되었음을 공지합니다. — “We announce that the schedule has changed.”

This structure treats the whole preceding clause as the content of the recognition or statement. It is compact and formal. In everyday speech, a speaker may instead use -는 것을/걸 or a quoted clause with -다고 depending on the governing verb and intended nuance.

-기 as a clause-level reason

In patterns such as -기 때문에, -기에, and -길래, the form participates in a larger connective expression. These are not always best understood as an ordinary noun plus a particle:

• 시간이 없기 때문에 택시를 탔어요. — “Because I had no time, I took a taxi.”
• 날씨가 좋기에 밖으로 나갔다. — “Since the weather was good, I went outside.”
• 사람들이 줄을 서 있길래 저도 기다렸어요. — “I saw people lining up, so I waited too.”

The last two have their own register and viewpoint nuances. Learn them as later extensions rather than assuming every 기 has exactly the same activity meaning.

Sentence-final -(으)ㅁ in notes and records

A notice, diary entry, meeting minute, or checklist may end in -(으)ㅁ:

• 오후 세 시에 회의함. — “Meeting at 3 p.m.”
• 검토 결과 이상 없음. — “Review result: no issues.”
• 모든 참가자가 동의했음. — “All participants agreed.”

This impersonal written ending records information without the social politeness endings used in speech. It can sound abrupt or bureaucratic if used in an ordinary conversation. Online, people may also use final -ㅁ/음 playfully or tersely, but that does not make it a neutral substitute for -아요/어요.

Ambiguity and the subject of the embedded action

Korean often omits a subject when context identifies it. In 운전하기가 어려워요, the person finding driving difficult may be the speaker, or the sentence may make a general statement. Add a subject when needed: 저는 밤에 운전하기가 어려워요 means “I find it difficult to drive at night.” With a different embedded actor, context and particles must make the relation clear: 아이가 혼자 가기가 어려워요 “It is difficult for the child to go alone.”

Practice Tips

1. Sort examples by function, not translation. Make three columns headed “activity,” “fact/state,” and “concrete action.” Place new examples under -기, -(으)ㅁ, or -는 것 and explain your choice aloud.
2. Memorize complete frames. Build five personal sentences with -기를 좋아하다, -기 쉽다, -기로 하다, -기 위해, and -(으)ㅁ을 확인하다. This prevents unnatural swapping between the endings.
3. Collect real-world written forms. Look at Korean notices, app menus, forms, and meeting notes for 없음, 있음, 완료함, and 확인했음. Then rewrite each item as a normal polite spoken sentence to feel the register contrast.

Related Concepts

• Prerequisite: Verb and Adjective Forms That Modify Nouns — helps you understand the alternative -는 것 structure and how Korean clauses describe nouns.