verb + ~지 않다 (~ji anta)

Verb (or adjective) stem + 지 않다 is the long form of negation. It means the same as 안 + verb: it says that something does not happen or is not the case. With actions it often implies that the subject could do it but does not (by choice), unlike -지 못하다, which means the subject cannot do it.

Conjugate 않다 for the politeness level: 먹지 않아, 먹지 않아요, 먹지 않습니다.

For example, '아침을 먹지 않았어요.' (I didn't have breakfast.) means the same as '아침을 안 먹었어요.' The -지 않다 form sounds slightly more formal and is common in writing.