Answer:

opposer

Answer	Crossword Clue
OPPOSER	Anti
OPPOSER	One against
OPPOSER	Anti.

OPPOSER	Combatant.
OPPOSER	"No" voter
OPPOSER	Enemy
OPPOSER	Supporter's foe

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.