An antigram is a word or phrase whose letters can be rearranged to produce an opposite meaning:

ABET = BEAT
ABOMINABLE = BON, AMIABLE
ADVERSARIES = ARE ADVISERS
ANTAGONIST = NOT AGAINST
BOASTING = IT’S NO GAB
COMMENDATION = AIM TO CONDEMN
CONVENTIONAL = I VOTE NON-CLAN
DEFIANT = FAINTED
DEMONIACAL = A DOCILE MAN
FASHIONABLE = FINE? HA, A SLOB!
FILLED = ILL-FED
FORBID = BID FOR
HIBERNIANS = BANISH ERIN
HOME RUN HITTER = I’M NOT RUTH HERE
HONESTLY = ON THE SLY
HONOREES = NO HEROES
INDISCRIMINATE = DISCERN AIM IN IT
INNERMOST = I NEST ON RIM
LEGION = LONE GI
NOMINATE = I NAME NOT
PROSPEROUS = POOR PURSES
ROUSING = SOURING
THOMAS A. EDISON = TOM HAS NO IDEAS
TIMBERLESS = TREES, LIMBS
WOMANISH = HOW MAN IS

Without any rearrangement at all, IMPARTIALLY can be read as I’M PART, I ALLY. And DEFENCE is DE-FENCE!