a word or phrase that is often used with another word or phrase, in a way that sounds correct to people who have spoken the language all their lives, but might not be expected from the meaning

In the phrase "a hard frost", "hard" is a collocation of "frost" and "strong" would not sound natural. 在短语 a hard frost 中，hard 可与 frost 搭配，用 strong 则听上去不自然。

the combination of words formed when two or more words are often used together in a way that sounds correct

The phrase "a hard frost" is a collocation. 短语 a hard frost 是习惯搭配。

the regular use of some words and phrases with others, especially in a way that is difficult to guess