mental reservation vs arriere pensee

mental reservation and arriere pensee both are nouns.

Word	Noun	Adjective	Verb	Adverb
mental reservation	Yes	No	No	No
arriere pensee	Yes	No	No	No

As nouns, mental reservation and arriere pensee are synonyms defined as:

mental reservation and arriere pensee: an unstated doubt that prevents you from accepting something wholeheartedly

Other synonyms of mental reservation include reservation.

mental reservation (noun)	arriere pensee (noun)
an unstated doubt that prevents you from accepting something wholeheartedly	an unstated doubt that prevents you from accepting something wholeheartedly