Synonyms for Objection:

n.

support, squawk, demur. •argument, disagreement (noun)
dislike, declination, exception, odium, grievance, disesteem, demur, challenge, dissatisfaction, displeasure, opposition, discontent, squawk, disinclination, doubt, hesitation, question, disapproval, remonstrance, unwillingness, protest, scruple, disapprobation, kick, rejection, criticism, censure.
•condemnation (noun)
disapproval.
•criticism (noun)
faultfinding, censure.
•disapproval (noun)
displeasure, disapprobation.
•objection (noun)
dissent, protest, remonstrance, expostulation.
•opposition (noun)
challenge, counterattack, disagreement, protest, obstruction, defiance, dispute, opposition, repulsion, hindrance, fight, interference, obstinacy, inhibition, contradiction, rebuff, confrontation, friction, counteraction, conflict, antagonism, suppression, repression, adversary, resistance, impediment.
•protest (noun)
scold, grievance, disparagement, lamentation, denigration, complaint, deprecation, ridicule, detraction.

Other synonyms:

disapproval. kick, dissatisfaction, clamor. exception. beef. •aversion
dislike.
•censure
reproof, criticism, blame.
•challenge
demurrer.
•denunciation
condemnation.
•discredit
reproach.
•disgust
revulsion.
•dissent
dissent.
•grievance
plaint.
•reluctance
disinclination.

Usage examples for objection

1. He couldn't see the objection – Space Viking by Henry Beam Piper

2. He slowly turned to the prisoner: " Have you any objection to these letters being read?" – Hand and Ring by Anna Katharine Green

3. But suppose this were not so, to what would the objection amount? – Woman: Man's Equal by Thomas Webster