1.The act of expressing; the act of forcing out by pressure; as, the expression of juices or oils; also, of extorting or eliciting; as, a forcible expression of truth.
2.The act of declaring or signifying; declaration; utterance; as, an expression of the public will. "With this tone of philosophy were mingled expressions of sympathy."
3.Lively or vivid representation of meaning, sentiment, or feeling, etc.; significant and impressive indication, whether by language, appearance, or gesture; that manner or style which gives life and suggestive force to ideas and sentiments; as, he reads with expression; her performance on the piano has expression. "The imitators of Shakespeare, fixing their attention on his wonderful power of expression, have directed their imitation to this."
4.That which is expressed by a countenance, a posture, a work of art, etc.; look, as indicative of thought or feeling. "The expression of an eye." "It still wore the majesty of expression so conspicuous in his portraits by the inimitable pencil of Titian."
5.A form of words in which an idea or sentiment is conveyed; a mode of speech; a phrase; as, a common expression; an odd expression.
6.(Math.) The representation of any quantity or relation by appropriate characters or symbols, usually in a specific order.
7.(Genetics) The production of products by a gene that cause the appearance of the corresponding protein or phenotype; of a gene or of an organism with a specific gene; as, the expression the beta-galactosidase positive phenotype,
8.(Computers) A combination of characters linked by operators, occurring as part of the code of a computer program, which must be evaluated according to the rules of the computer language in order to produce a resulting value. Note: In most programming languages, (a + b) is an expression indicating simple arithmetic addition, if the variables a and b are real numbers. Many other types of operation may be used in programs, and each set of symbols indicating an operation is an expression in that program.
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