1650s, "capricious," from freak (n.) + -ish. Meaning "grotesque" is recorded from 1805. Related: Freakishly; freakishness. Keats has freakful.
freakish weather
a freakish extra toe
a freakish combination of styles
fraulein
fray
frayed
frazzle
freak
freakish
freak-out
freaky
freckle
Freddie Mac
Frederick