Source : Webster's Revised Unabridged Dictionary (1913)

Hobby \Hob"by\, n.; pl. {Hobbies}. [OE. hobi; cf. OF. hobe,
   hob['e], F. hobereau a hobby, a species of falcon. OF. hober
   to move, stir. Cf. {Hobby} a horse.] (Zo["o]l.)
   A small, strong-winged European falcon ({Falco subbuteo}),
   formerly trained for hawking.