innominable (adj.)

"unnameable," late 14c., from Old French innominable, from Late Latin innominabilis "that cannot be named," from in- "not, opposite of" (see in- (1)) + *nominabilis, from Latin nominalis "pertaining to a name or names," from nomen (genitive nominis) "name" (from PIE root *no-men- "name"). In jocular use, innominables = "trousers" (1827; see inexpressible).