caveat emptor

"warning, hint of caution," 1550s, Latin, literally "let him beware," 3rd person singular present subjunctive of cavere "to beware, take heed, watch, guard against," from PIE root *keu- "to see, observe, perceive." Legal sense "public warning preventing some action" is from 1650s.

late 14c., "not subject to (a rule, law, authority, etc.)," from Old French exempt (13c.) and directly from Latin exemptus, past participle of eximere "remove, take out, take away; free, release, deliver, make an exception of," from ex "out" (see ex-) + emere "to buy," originally "to take," from PIE root *em- "to take, distribute." Also in Middle English in a more general sense, "taken away, cut off (from), removed (from)."