bête noire (Fr.). A black beast; a bugbear.
bis dat qui cito dat (L.). He gives twice who gives quickly.
bon ami (Fr.). Good friend.
bon jour (Fr.). Good day; good morning.
bon soir (Fr.). Good evening.
Cacoethes loquendi, scribendi (L.). An itch for speaking, writing.
carpe diem (L.). Enjoy the present day; improve the time.
carte blanche (Fr.). A white card; full power.
casus belli (L.). The occasion or cause of war.
cela va sans dire (Fr.). That goes without saying.