HSK 6 · VERSION 2.0#10
Expressing “Certainly” with “bìdìng”
必定
How it works
必定 (bìdìng) means “certainly,” “surely,” or “bound to.” It expresses a high degree of certainty, often based on logic, judgment, or strong belief.
Compared with 一定 (yídìng), 必定 (bìdìng) often sounds more formal or literary.
Example sentences
任何事情只要长期坚持下去，必定会在某个阶段看见成果。
As long as one persists with anything over a long period of time, one is sure to see results at some stage.
他既然已经下了这么大的决心，接下来必定不会轻易半途而废。
Since he has already made such a great determination, he certainly will not give up halfway easily.
从这些细节判断，背后必定还有我们暂时没有掌握的信息。
Judging from these details, there must be additional information that we have not yet uncovered.
Key point
必定 (bìdìng) often appears in formal reasoning, prediction, or assertion.