(n) The act of articulating, conveying, or representing in terms, art, music, or activity; a manifestation: an expression of outlying values.
(n) a thing that expresses or communicates: Let this plaque act as a manifestation of our esteem.
(n) Mathematics emblematic or mix of signs that represents a quantity or a relationship between quantities.
expression in Technology Dictionary
An expression is a certain concept in computer science for which many variables or constants, and operators and functions, are placed collectively in a single declaration which acted on by a certain program writing language. by Vera AnkneyReport definition