1To accept and agree to someone's opinion or conditions; to consent.
彼は上司の提案に納得して、プロジェクトに参加した。
He agreed to his boss's proposal and joined the project.
契約の条件に納得できないなら、サインしないほうがいい。
If you can't agree to the contract terms, you shouldn't sign.
両者が納得した上で、契約が成立した。
The contract was concluded after both parties reached agreement.
2Understanding and being fully satisfied or convinced, as after hearing an explanation ("I see, that makes sense").
説明を聞いてようやく納得できた。
After hearing the explanation, I was finally convinced.
彼の言い訳には納得がいかない。
I can't accept his excuse.
どうしてそうなるのか、納得がいくまで質問した。
I kept asking questions until I understood why that happened.