Core Pattern Rule: Using -기 for Promises and Lists
The -기 ending is a simple yet powerful tool for turning a verb into a noun phrase. In this pattern, it's used to end a sentence, creating a concise statement that functions like a promise, a resolution, a rule, or an item on a to-do list.
Meaning & Usage
Meaning: It nominalizes the verb, essentially turning "to do [verb]" into a standalone statement. Think of it as a label for an action.
When to use: Use it for making personal resolutions (like for the New Year), setting ground rules with someone, or writing down a list of tasks. It has a declarative, slightly impersonal tone.
Formation
It's very simple: just attach -기 directly to the verb stem, regardless of whether it ends in a vowel or a consonant.
하다 (to do): 하 + 기 → 하기
먹다 (to eat): 먹 + 기 → 먹기
않다 (to not do): 않 + 기 → 않기 (e.g., 지각하지 않기 - No being late)
지각하지 않기. / 밥 잘 챙겨 먹기. / 한국어 열심히 공부하기. / 포기하지 않기.
Native Nuance & Mistakes
While -기 is a sentence-ending form, it's not a typical conversational sentence. Understanding its specific function is key to using it naturally.
It's a Fragment, Not a Full Sentence
Think of -기 endings as bullet points or headlines. They state a topic or a rule without the grammatical structure of a full sentence like "I will..." or "You should...".
Correct: 방 청소하기. (As a to-do list item: "Clean room.")
Incorrect: 저는 방 청소하기. (To mean "I am cleaning my room." You should say 저는 방 청소해요.)
Context is Everything
This pattern is used in specific contexts like setting goals, making promises, or listing rules. It's not used for general narration or describing ongoing actions. You'll often see it on signs, in rulebooks, or hear it when people are making firm agreements.
Natural: (Making a New Year's resolution) 새해 목표: 돈 아껴 쓰기, 긍정적으로 생각하기.
Awkward: (Telling a friend what you did) 어제 친구랑 약속 지키기. (Should be: 어제 친구랑 약속 지켰어요.)
지키지 못할 약속 하지 않기. / 자신을 사랑하기. / 긍정적으로 생각하기.
Common Combinations: -기로 하다 / -기로 약속하다
The -기 nominalizer is a building block for other important grammar patterns related to decisions and promises. Recognizing this connection will deepen your understanding.
-기로 하다: To Decide To...
This pattern is used to express a decision or resolution you have made.
Structure: Verb Stem + -기로 하다
Example: 매일 운동하기로 했어요. (I decided to exercise every day.)
Example: 술을 마시지 않기로 했어요. (I decided not to drink alcohol.)
-기로 약속하다: To Promise To...
This pattern is used to state that you have made a promise to do (or not do) something.
Structure: Verb Stem + -기로 약속하다
Example: 우리 다시는 싸우지 않기로 약속해요. (Let's promise not to fight again.)
Example: 거짓말하지 않기로 약속해. (Promise not to lie.)
These patterns take the "action label" created by -기 and embed it into a full sentence about making a decision or promise.
내일부터 한국어 열심히 공부하기로 했어요. / 우리 거짓말하지 않기로 약속해요. / 지각하지 않기로 약속해.
Politeness & Formality
This pattern has a clear distinction between casual and polite forms, which you can hear in the practice lines. The choice depends on who you are speaking to.
Casual Form: -기
Usage: This is the base form. It's used when talking to yourself (making a mental note), writing a personal to-do list, or speaking to close friends or people younger than you.
Tone: It can sound quite direct, like a command or a firm declaration. For example, a parent might say 싸우지 않기! (No fighting!) to their children.
Polite Form: -기요
Usage: Simply add 요 to make the statement polite. Use this when speaking to someone older, a superior, or anyone you would normally use 해요체 with.
Tone: Adding 요 softens the directness and shows respect. For example, if a doctor is giving you instructions, they might say 매일 운동하기요. (Exercise every day.) to be both clear and polite.
싸우지 않기. / 싸우지 않기요. / 엄마한테 전화하기. / 엄마한테 전화하기요.