Source : Webster's Revised Unabridged Dictionary (1913)

Hagbut \Hag"but\, n. [OF. haquebute, prob. a corruption of D.
   haakbus; haak hook + bus gun barrel. See {Hook}, and 2d
   {Box}, and cf. {Arquebus}.]
   A harquebus, of which the but was bent down or hooked for
   convenience in taking aim. [Written also {haguebut} and
   {hackbuss}.]

Source : WordNet®

hagbut
     n : an obsolete firearm with a long barrel [syn: {arquebus}, {harquebus},
          {hackbut}]