WordNet sense 1 (an opening made forcibly as by pulling apart):

rent, rip, snag, tear, tear

WordNet sense 2 (having been divided; having the unity destroyed):

disconnected, fragmented, disunited

WordNet sense 3 (separated into parts or pieces):

divided

WordNet sense 4 (separate into parts or portions):

dissever, divide, separate, separate, carve up, split up

WordNet sense 5 (discontinue an association or relation; go different ways):

break, part, break up

WordNet sense 6 (separate or cut with a tool, such as a sharp instrument):

cleave, rive

WordNet sense 7 (separated into parts or laid open or penetrated with a sharp edge or instrument):

cut

WordNet sense 8 (an increase in the number of outstanding shares of a corporation without changing the shareholders' equity):

stock split

WordNet sense 9 (division of a group into opposing factions):

schism

WordNet sense 10 (break open or apart suddenly):

burst, break open