Synonyms for Throw In (same or very similar meaning)
WordNet sense 1 (give up in the face of defeat of lacking hope; admit defeat):
quit, give up, drop out, chuck up the sponge, drop by the wayside, fall by the wayside, throw in the towelWordNet sense 2 (to insert between other elements):
inject, interject, interpose, come in, put inFrom the ODE community, based on WordNetadd/edit