As a Verb
1. to write down, note down
As in: 记事 ji4shi4 notes
记载〔記載〕ji4zai4 record (verb or noun)
登记〔-記〕 deng1ji4 register
2. to remember
As in:
记仇〔記-〕ji4chou2 harbour bitter resentment
记仇〔記-〕 ji4dian4 to keep thinking about
死记硬背〔-記--〕si3ji4-ying4bei4 to learn by rote
As a Noun:
1. A mark
标记〔標記〕biao1ji4 a sign mark or symbol