WordNet sense 1 (come down on or keep down by unjust use of one's authority):

crush, oppress

WordNet sense 2 (control and refrain from showing; of emotions):

bottle up

WordNet sense 3 (keep under control; keep in check):

keep, restrain, hold back, keep back

WordNet sense 4 (put out of one's consciousness):

repress, repress

WordNet sense 5 (to put down by force or authority):

conquer, curb, inhibit, subdue, stamp down