1. 成语性词语：end connector 终接器; 终端盒; (履带的)联结片 | idiomatic expression 成语性词语 | mercast pattern (冰冻)水银模

2. 习惯表达：idiom习语 | idiomatic expression习惯表达 | idiomaticity习语程度

noun

1. an expression whose meanings cannot be inferred from the meanings of the words that make it up

Synonym: idiomphrasal idiomset phrasephrase