(usu + to) to represent (something or somebody) as similar to another thing or person; to liken
Shall I compare thee to a summer's day? — Shakespeare
(often + to/with) to examine the character or qualities of (something or somebody) in order to discover resemblances or differences
We compared the two paintings
I compared her signature with the one on the letter
in grammar, to inflect or modify (an adjective or adverb) according to the degrees of comparison
(+ with) to be similar, or different in a specified way
This year's sales figures compare favourably with last year's
compare notes
to exchange information or opinions
[Middle English comparen via French from Latin comparare to couple, compare, from compar like, from com- + par equal]