What is “이다”?

“이다” is a postpositional particle that attaches to a noun or certain adverbs to function as the main descriptive (or copular) element of a sentence. Essentially, it links the subject and the predicate to complete the sentence’s meaning.

1. Usage

Descriptive (Copular) Particle

“이다” attaches to the word that describes or defines the subject, thereby conveying the core information of the sentence.

• Preceding element: Typically a noun (or certain adverbs).
• Following element: After “이다,” various verb endings can be added. It can also appear in a final form to end a sentence.

Examples:

• 나는 직장인이다. (I am an office worker.)
• 저것은 트럭이다. (That is a truck.)
• 나는 열 일곱 살이고 언니는 스무 세 살이다. (I am 17 years old, and my sister is 23 years old.)
• 이건 내가 직접 키운 식물이다. (This is a plant I grew by myself.)

2. Additional Context (Discourse Information)

Honorific Expression in Final Form

“이다” by itself does not carry an honorific or polite ending. To show respect when concluding a sentence, use “입니다” or “-이에요/-예요.”

• Example: 할아버지, 우리 집은 이쪽입니다/이에요. (Grandfather, our home is this way.)
• *Note: Using “이쪽이다” in a final sentence is not polite or natural in formal speech.

Subject Honorification

To honor the subject (rather than the listener), add “-(으)시-” after “이다.”

• Example: 저희 선생님은 남자분이십니다. (My teacher is a man.)

3. Fill-in-the-Blank Quiz

Complete each sentence with the appropriate form of “이다”:

1. 나는 직장인___. (I am an office worker.)
2. 저것은 트럭___. (That is a truck.)
3. 이건 내가 직접 키운 식물___. (This is a plant I grew by myself.)
4. 저희 선생님은 남자분___. (My teacher is a man.)

4. Answers

• 나는 직장인이다.
• 저것은 트럭이다. 
• 이건 내가 직접 키운 식물이다.
• 저희 선생님은 남자분이십니다.