arrière-pensée

noun

ar·​ri·​ère-pen·​sée ˌa-rē-ər-päⁿ-ˈsā 

: mental reservation

Word History

Etymology

borrowed from French, "ulterior motive, mental reservation," from arrièrre "back, rear" (going back to Old French arriere, adverb, "back, behind") + pensée "thought" — more at arrear, pansy

First Known Use

1617, in the meaning defined above