Synonyms for Swear (same or very similar meaning)
WordNet sense 1 (make a deposition; declare under oath):
depose, deponeWordNet sense 2 (to declare or affirm solemnly and formally as true):
affirm, assert, aver, avow, swan, verifyWordNet sense 3 (utter obscenities or profanities):
blaspheme, curse, cuss, imprecateWordNet sense 4 (have confidence or faith in):
bank, rely, trustFrom the ODE community, based on WordNetadd/edit