Pronunciation: (ik-spresh'un),[key] —n. 1. the act of expressing or setting forth in words: the free expression of political opinions. 2. a particular word, phrase, or form of words: old-fashioned expressions. 3. the manner or form in which a thing is expressed in words; wording; phrasing: delicacy of expression. 4. the power of expressing in words: joy beyond expression. 5. indication of feeling, spirit, character, etc., as on the face, in the voice, or in artistic execution: the lyric expression embodied in his poetry. 6. a look or intonation expressing personal reaction, feeling, etc.: a shocked expression. 7. the quality or power of expressing an attitude, emotion, etc.: a face that lacks expression; to read with expression. 8. the act of expressing or representing, as by symbols.
9. Math.a symbol or a combination of symbols representing a value, relation, or the like.
10. Ling.the stylistic characteristics of an utterance (opposed to meaning).
11. Ling.the system of verbal utterances specific to a language (opposed to content).
12. the act of expressing or pressing out.
13. Computers.a combination of variables, constants, and functions linked by operation symbols and any required punctuation that describe a rule for calculating a value.
14. Genetics. a. the action of a gene in the production of a protein or a phenotype.
b. expressivity (def. 2).