1. The act of expressing, conveying, or representing in words, art, music, or movement; a manifestation: an expression of rural values.

2. Something that expresses or communicates: Let this plaque serve as an expression of our esteem.

3. Mathematics A symbol or combination of symbols that represents a quantity or a relationship between quantities.

4. The manner in which one expresses oneself, especially in speaking, depicting, or performing.

5. A particular word or phrase: "an old Yankee expression ... 'Stand up and be counted'" (Charles Kuralt).

6. The outward manifestation of a mood or a disposition: My tears are an expression of my grief.

7. A facial aspect or a look that conveys a special feeling: an expression of scorn.

8. The act of pressing or squeezing out.

9. Genetics The act or process of expressing a gene.