'Unscrew' definitions:

Definition of 'unscrew'

From: WordNet
verb
Loosen something by unscrewing it; "unscrew the outlet plate"
verb
Loosen by turning; "unscrew the bottle cap" [ant: screw]

Definition of 'Unscrew'

From: GCIDE
  • Unscrew \Un*screw"\, v. t. [1st pref. un- + screw.] To draw the screws from; to loose from screws; to loosen or withdraw (anything, as a screw) by turning it. [1913 Webster]