Forswear comes from Old English forswerian ('to swear falsely, renounce on oath'), combining the prefix for- (here negating or away) with swerian ('to swear'). It means to renounce under oath. The development is chiefly inherited within English and its older relatives, with the later form continuing material already present in the language's ancestry. In present use, it is used as a verb meaning "to renounce or reject under oath; to abjure", so the historical material remains connected with the current sense rather than standing as bare ancestry. The wider English family includes derivatives such as forsworn and forswearer and related forms such as swear, showing how the same historical material continues to organize neighboring vocabulary. The named historical forms include Old English forswerian and Old English swerian, keeping the history tied to concrete forms rather than a loose resemblance.