Meaning of “expression” - Learner’s Dictionary

expression

noun uk us /ɪkˈspreʃən/
LOOK [ C ]

B2 the look on someone's face showing what they feel or think:

your facial expression
He had a sad expression on his face.
PHRASE [ C ]

B2 a phrase that has a special meaning:

'A can of worms' is an expression meaning a difficult situation.
SHOWING THOUGHTS [ C, U ]

B2 ways of saying what you think or showing how you feel using words or actions:

As an expression of our disapproval, we will no longer use his shop.

(Definition of “expression” from the Cambridge Learner’s Dictionary © Cambridge University Press)