1 : the act of making your thoughts, feelings, etc., known by speech, writing, or some other method : the act of expressing something
freedom of expression [=freedom to say and show what you feel and believe]
Dance is a form of artistic/creative expression.
She is always looking for new ways to give expression to [=to express] her ideas.
Her competitive spirit found expression [=was expressed] in sports.
an expression of affection
expressions of anger
2 [count] : a word or phrase
a slang expression
He uses some very odd expressions.
The expression “to make fun of” means “to ridicule.”
◊ People say excuse/pardon/forgive the expression when they are using a word or phrase that might offend or annoy someone.
When you first told me your plan, I thought you were, pardon the expression, crazy.
I'm so glad that you've decided to join us. In fact, I'm tickled pink, (if you'll) excuse the expression.
3 [count] : the way someone's face looks that shows emotions and feelings
Judging from her expression, I think the gift was a complete surprise.
We saw his expression change from angry/anger to sad/sadness.
She wore/had a smug expression.
4 [noncount] : a way of doing something (such as speaking or singing) that shows emotions and feelings
I told him to read the poem with more expression.
5 [count] mathematics : a symbol or a combination of symbols and signs representing a quantity or process
103 is an exponential expression.
— expressionless /ɪkˈsprɛʃənləs/ adjective
an expressionless face
— expressionlessly adverb
staring expressionlessly at the camera
— expressionlessness noun [noncount]