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.
If you paid close attention to your grade school teacher, you may be fortunate to know the difference between expressions and equations. An expression is basically an incomplete mathematical sentence. It is like any normal phrase in the English language. Compared to expressions, equations are more complete. They are homologous to what completely structured English sentences are.