Source : Webster's Revised Unabridged Dictionary (1913)

Plagiarize \Pla"gia*rize\, v. t. [imp. & p. p. {Plagiarized}; p.
   pr. & vb. n. {Plagiarizing}.]
   To steal or purloin from the writings of another; to
   appropriate without due acknowledgement (the ideas or
   expressions of another).