contra/counter

against, opposite

Spelled contra, counter, contro · contra 'against, opposite'; French contre gave English counter-

Latin contra meant against: contraband goes against a ban, a contrarian opposes prevailing views, and counteracting works against an effect.

Words built from it

contravene — to violate a rule or act against a principle
Latin contra (against) + venire (come) → contravenire → contravene
incontrovertible — impossible to dispute successfully
in- (not) + controvertible; controvert comes from Latin contra (against) + vertere (turn), with -ible (able to be)
counterfeit — made to pass dishonestly as something genuine
Old French contrefait, from contre (against, from Latin contra) + fait (made, from Latin facere), meant imitated
counteract — to oppose or reduce the effect of something
counter- (against, through French contre from Latin contra) + act
contraband — goods brought in, taken out, or possessed illegally
Italian contrabbando, from contra (against) + bando (public proclamation or ban)
contrarian — a person who tends to oppose prevailing opinions
contrary, ultimately from Latin contrarius (opposite), from contra (against), + -an (person)

contract — Its contra letters cross a boundary: Latin con- means together and trahere means pull. The prefix is con-, not contra-.