개

In a sentence

• 개가 뛰고 있습니다.

  The dog is running.

  Here, '개' refers to a dog, an animal, and serves as the subject of the sentence.

• 나는 세 개의 사과를 샀어요.

  I bought three apples.

  Here, '개' is used as a counting unit for items, indicating the number of apples in this example.

• 이것은 정말 개맛있다.

  This tastes really incredibly good.

  Here, '개' is used colloquially as an intensifier to emphasize the degree of the adjective '맛있다' (delicious).