immunoglobulin G. Our Living Language Igg, a shortened form of ignore, seems to have come into American speech from jive, the special jargon of Black jazz musicians in the 1930s. Its use has since spread beyond musicians into African-American communities throughout the United States. The reduction of a word to its initial syllable is a common source of slang or informal words, especially among groups of speakers who for reasons of exclusivity like to remain avant-garde in their speech. Often such words come into general use, as in mike for microphone