case: Not to be applied to persons. The expression sometimes used of an eccentric or vicious person, "He is a case" or "a hard case," is an objectionable colloquialism.
casket, which is from the French casque, helmet, is frequently now used in the United States as a euphemism for coffin, which is from the Greek kophinos, basket. Such innovations are not to be recommended. They savor of pedantry, or, worse still, of pride. If coffin is not good enough for the worthy deceased or for his purse-proud relatives, why rest content with the simple casket, when by a mere figure of speech sarcophagus may save the reputation of both the living and the dead?
casuality is an obsolete form of casualty, and should be treated as such.
cataclasm and cataclysm are often interchanged. The Greek kata, down, is combined in the one case with klaō, break, and in the other with klyzo, wash. Where sudden overwhelming change is intended, as by revolution, cataclasm is to be preferred to cataclysm, which, though sometimes used to signify such a change, is strictly applied to an overwhelming flood of water, and, specifically, to the Noachian deluge.
catch on, to: A colloquialism having two distinct meanings, the first bordering on the vulgar, is used by persons with little sense of refinement in speech