Learner's definition of EXPRESSION
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.
2 [count] : a word or phrase
◊ 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 5 [count], mathematics : a symbol or a combination of symbols and signs representing a quantity or process