resister

Nouns

(n) someone who systematically obstructs some action that others want to take obstructer, obstructionist, obstructor, thwarter,
(n) someone who offers opposition adversary, antagonist, opposer, opponent,

Synonyms

obstructer obstructionist obstructor thwarter adversary antagonist opposer opponent

Antonyms

agonist

Words of close approximity

resistor