不见得【bújiànde】

不见得 casts doubt on a claim: "not necessarily", "I doubt it". It goes before the verb or adjective, and it's at home in speech and everyday writing.

As a reply

不见得 can stand alone as a short, slightly sceptical answer to what someone has just said.

不见得 or 不一定

不一定 is neutral: it may or may not happen. 不见得 leans towards "probably not" and argues with an expectation.

Placement

Like other adverbs, 不见得 goes before the verb or adjective, not at the end of the clause as "not necessarily" can in English.

• × 这个办法有用不见得 → 这个办法不见得有用
• × 他会来不见得 → 他不见得会来

未必 is the written equivalent and has its own entry.