Jackinthegreen
Explorer
That's strange. No D&D book I've ever read uses the term for anything other than githyanki fighter/magic-users.
That's because the books themselves rarely if ever mention that since it's a player term. The player base has taken it very much to heart, however, and it is a mainstay in the 3.X lexicon and will always remain so because it's that deeply rooted and easy to use. GiTP certainly has it going on, and a visit to MinMaxBoards will reveal the optimizers also use the term.
I hope you weren't too attached to its previous definition.