'Undock' definitions:

Definition of 'undock'

From: WordNet
verb
Move out of a dock; "We docked at noon" [ant: dock]
verb
Take (a ship) out of a dock; "undock the ship" [ant: dock]

Definition of 'Undock'

From: GCIDE
  • Undock \Un*dock"\, v. t. [1st pref. un- + dock.] (Naut.) To take out of dock; as, to undock a ship. [1913 Webster]