ILF

ILF was acronymic slang, or perhaps academic or bureaucratic jargon, for the expression, "intelligent life form". It was used by the humans on the expedition to Deva Loka to describe the planet's native sentient life, the Kinda. It was unknown how broadly the term was used amongst other humans of that time, but the Fifth Doctor seemed unfamiliar with the expression. (DW: Kinda)