This is the 9819th most frequent French word.
expression
The act of conveying thoughts, feelings, or ideas through speech, writing, art, or other forms.
In this sentence, 'expression' is used to denote the act of conveying a feeling or emotion, in this case, happiness.
Son expression du bonheur était contagieuse.
Her expression of happiness was contagious.
Here, 'expression' refers to the manifestation of creativity or ideas, specifically in an artistic form.
Il recherche une manière originale d'expression artistique.
He seeks an original way of artistic expression.
In this context, 'expression' is referring to a linguistic construct, specifically an idiomatic phrase.