Late Middle English; earliest use found in Guy de Chauliac's Grande Chirurgie. Origin uncertain; perhaps compare Middle Low German forms with voiceless final consonant at plug, but these do not show an exact semantic or formal parallel. (For evidence of a possible loan in Older Scots from such Middle Low German forms see Dict. Older Sc. Tongue s.v. pluk-, ploukin(g vbl. n.1 ‘the action of inserting a plug or wedge into a hole or aperture in a barrel in order to stop it up’.).