According to Gems: A Lively Guide for the Casual Collector by Daniel J. Dennis, this word means "not of the family" (he doesn't say what language this is from). A Malaia garnet is one which is composed of three different materials, all of which are considered garnet: almandine, pyrope, and spessartine. The name was given to the mixed-type garnets when they were first found in Tanzania and Kenya.