[1] : The Collaborative International Dictionary of English v.0.48

barn \barn\ baumrn, n. oe. bern, as. berern, bern; bere
   barley + ern, aern, a close place. root92. see barley.
   a covered building used chiefly for storing grain, hay, and
   other productions of a farm. in the united states a part of
   the barn is often used for stables.
   1913 webster

   barn owl zool., an owl of europe and america aluco
      flammeus, or strix flammea, which frequents barns and
      other buildings.

   barn swallow zool., the common american swallow hirundo
      horreorum, which attaches its nest of mud to the beams
      and rafters of barns.
      1913 webster
see also:
barley barn owl aluco flammeus strix flammea barn swallow hirundo horreorum 

[2] : WordNet (r) 2.0

barn swallow
     n : common swallow of north america and europe that nests in
         barns etc. syn: chimney swallow, hirundo rustica
see also:
chimney swallow hirundo rustica 

Barn >> B Words
Barn, definition of term: Barn
barn_pag1.html

Swallow >> S Words
Swallow, definition of term: Swallow
swallow_pag1.html

Barn Owl >> B Words
Barn Owl, definition of term: Barn Owl
barn+owl_pag1.html