human, individual, mortal, person, somebody, someone, soul - a human being; "there was too much for one person to do"

contester - someone who contests an outcome (of a race or an election etc.)

accuser - someone who imputes guilt or blame

arguer, debater - someone who engages in debate

denier - one who denies

hairsplitter - a disputant who makes unreasonably fine distinctions

logomach, logomachist - someone given to disputes over words

obstructer, obstructionist, obstructor, resister, thwarter - someone who systematically obstructs some action that others want to take

quarreler, quarreller - a disputant who quarrels

caviler, caviller, quibbler, pettifogger - a disputant who quibbles; someone who raises annoying petty objections

crusader, meliorist, reformer, reformist - a disputant who advocates reform