defender

noun

1 the defenders of the rural environment:

protector, guard, guardian, preserver, bodyguard;

custodian, watchdog, keeper, overseer, superintendent, caretaker, steward, trustee.

2 a defender of personal freedom:

supporter, upholder, backer, champion, advocate, endorser, sustainer, bolsterer, apologist, proponent, exponent, promoter, apostle, standard-bearer, torchbearer, flagbearer, adherent, believer.

▷antonyms attacker, critic.

3 he burst between two defenders and cracked a shot at the bar:

full back, back, sweeper;

(defenders) back four.

▷antonyms attacker, striker.

defender Oxford Dictionary of English