OBSCURE AND UNUSUAL WORDS

1) arriere-pensee

arree air pon say (noun)
: a mental reservation
: an unspoken intention

Early 19th century. From French, literally
"behind- thought," from the concealing of the thought.

2) betise
bay teez (noun)
: mildly ridiculous action or remark

Early 19th century. From French, from bete
"foolish,"from Old French beste "beast."