Merriam-Webster's Collegiate® Dictionary, 11th Edition
FREAK
I. noun
Etymology: origin unknown
Date: 1563
1. a sudden and odd or seemingly pointless idea or turn of the mind, a seemingly capricious action or event, a whimsical quality or disposition, one that is markedly unusual or abnormal: as, a person or animal having a physical oddity and appearing in a circus sideshow, b. slang a sexual deviate, a person who uses an illicit drug, hippie , an atypical postage stamp usually caused by a unique defect in paper (as a crease) or a unique event in the manufacturing process (as a speck of dirt on the plate) that does not produce a constant or systematic effect,
4. an ardent enthusiast , a person who is obsessed with something ,
II. adjective
Date: circa 1887
having the character of a freak ,
III. verb
Date: 1964
transitive verb to make greatly distressed, astonished, or discomposed, to put under the influence of a psychedelic drug, intransitive verb to withdraw from reality especially by taking drugs, to experience nightmarish hallucinations as a result of taking drugs,
3. to behave irrationally or unconventionally under the influence of drugs, to react with extreme or irrational distress or discomposure, freaked adjective freaked-out adjective
IV. transitive verb
Etymology: perhaps from or akin to 1freckle
Date: 1637
to streak especially with color