Webster's Revised Unabridged Dictionary · 1913

Freak

Freak (frēk) , transitive verb

[Akin to Old English frakin, freken, freckle, Icelandic freknur, pl., Swedish frakne, Danish fregne, Greek perkno`s dark-colored, Sanskrit prcni variegated. Compare Freckle, Freck.]

To variegate; to checker; to streak. [Rare]
Freaked with many a mingled hue. — Thomson

Freak , noun

[Probably from Old English frek bold, Anglo-Saxon frec bold, greedly; akin to Old High German freh greedly, German frech insolent, Icelandic frekr greedy, Gothic faíhufriks avaricious.]

1.
A sudden causeless change or turn of the mind; a whim of fancy; a capricious prank; a vagary or caprice.
She is restless and peevish, and sometimes in a freak will instantly change her habitation. — Spectator
2.
a rare and unpredictable event; as, the July snowstorm was a freak of nature.
3.
an habitual drug user, especially one who uses psychedelic drugs.
4.
an animal or person with a visible congenital abnormality; -- applied especially to those who appear in a circus sideshow.

Freak , intransitive verb

1.
to react with irrationality or extreme emotion; to lose one's composure; -- often used in the phrase freak out.
2.
to become irrational or to experience hallucinations under the influence of drugs; -- often used in the phrase freak out.

Freak , transitive verb

1.
to cause (a person) react with great distress or extreme emotion; -- often used in the phrase freak out.