c. 1400, "not summoned," from un- (1) "not" + past participle of call (v.). Similar formation in Swedish okallad, Danish ukaldet. With for and sense of "unnecessary, intrusive" it is first attested 1610.
unbroken
unbuckle
unburden
unburied
unbutton
uncalled
uncanny
uncap
uncaring
unceasing
uncensored