to stand up to someone
to not allow yourself to be treated badly, especially by someone in authority
to stand up for someone
to support or defend a person when they are being attacked
to stand firm
to not change your actions or opinions
fed up
bored or frustrated and unhappy (especially with a situation which has gone on too long)
back down
yield in an argument; withdraw your position
fight back
Defend yourself, resist an attack.
give in
to admit defeat; to reluctantly stop arguing
