termagant was found on page 127 of Marge Piercy's excellent Sex Wars.
In the context (according to Webster's New World Dictionary, Third College Edition), it means a boisterous, quarrelsome, scolding woman; shrew.
When capitalized it means an imaginary deity supposed by medieval Christians to be worshiped by Muslims and represented in morality plays as a boisterous, overbearing figure. In fact that is the derivation of the word which was spelled Tervagant in Middle English and came from Old French, probably introduced by the Crusaders.
Very interesting! Of course, we all know that women should never be boisterous or quarrelsome or scolding. Yet medieval Christians thought that Muslims considered this sort of person to be a deity.
My sentence: Beware of any man calling you a termagant.