She looked at him curiously - at his ugly tweed suit, his yellow boots, and up into the strong, forceful face with eyes set in deep hollows under his protruding brows, at the heavy jaws giving a certain coarseness to his expression, which his mouth and forehead, well-shaped though they were, could not altogether dispel.
Definition of Expression. An Expression is a mathematical phrase that combines numbers and/or variables using mathematical operations. An expression is a representation of a value; for example, variables and/or numerals that appear alone or in combination with operators are expressions.
Definition of expression for Students. 1  1 : the act or process of making known especially in words. 2  2 : a meaningful word or saying Grandpa uses old-fashioned expressions. 3  3 : the look on someone's face She had a pleased expression. 4  4 : a way of speaking, singing, or playing that shows mood or feeling She read her lines with expression.