hav·oc / ˈhavək/ • n. widespread destruction: the hurricane ripped through Florida, causing havoc. ∎  great confusion or disorder: schoolchildren wreaking havoc in the classroom.• v. (hav·ocked, hav·ocking) [tr.] archaic lay waste to; devastate.PHRASES: play havoc with completely disrupt; cause serious damage to: shift work plays havoc with the body clock.

havoc in phr. cry havoc sound the signal for spoliation; hence make havoc (of) plunder, devastate. XV. — AN. havok, alt. of OF. havo(t), of unkn. orig.