Synonyms for Overwhelm (same or very similar meaning)
WordNet sense 1 (overcome, as with emotions or perceptual stimuli):
overcome, overpower, overtake, whelm, sweep overWordNet sense 2 (cover completely or make imperceptible):
drown, submergeWordNet sense 3 (overcome by superior force):
overmasterWordNet sense 4 (charge someone with too many tasks):
deluge, flood outFrom the ODE community, based on WordNetadd/edit