freak / frēk/ • n. 1. a very unusual and unexpected event or situation: the teacher says the accident was a total freak | [as adj.] a freak storm. ∎  (also freak of nature) a person, animal, or plant with an unusual physical abnormality. ∎ inf. a person regarded as strange because of their unusual appearance or behavior. ∎  inf. a person who is obsessed with or unusually enthusiastic about a specified interest: a fitness freak. ∎  inf. a person addicted to a drug of a particular kind: the twins were cocaine freaks.2. archaic a sudden arbitrary change of mind; a whim: follow this way or that, as the freak takes you.• v. 1. [intr.] inf. react or behave in a wild and irrational way, typically because of the effects of extreme emotion, mental illness, or drugs: I could have freaked out and started smashing the place up. ∎  [tr.] cause to act in such a way: he freaks guest stars out on show day.2. [tr.] archaic fleck or streak randomly: the white pink and the pansy freaked with jet.

freak sudden change (as of fortune), capricious notion XVI; capricious prank XVII; product of sportive fancy XVIII; monstrous individual of its kind XIX. prob. of dial. orig.
Hence as vb. variegate XVII (esp. pp. freaked); practise freaks XVII; gambol, frolic XIX.