late 14c., "insincere praise," from Old French adulacion, from Latin adulationem (nominative adulatio) "a fawning; flattery, cringing courtesy," noun of action from past participle stem of aduliari "to flatter," from ad- "to" (see ad-) + ulos "tail," from PIE *ul- "the tail" (cognates: Sanskrit valah "tail," Lithuanian valai "horsehair of the tail"). The original notion is "to wag the tail" like a fawning dog (compare Greek sainein "to wag the tail," also "to flatter;" see also wheedle).