From WordNet (r) 2.0 (August 2003) [wn]:
barn
n 1: an outlying farm building for storing grain or animal feed
and housing farm animals
2: (physics) a unit of nuclear cross section; the effective
circular area that one particle presents to another as a
target for an encounter [syn: b]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Barn \Barn\ (b[aum]rn), n. [OE. bern, AS. berern, bern; bere
barley + ern, [ae]rn, a close place. [root]92. 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]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Barn \Barn\, v. t.
To lay up in a barn. [Obs.] --Shak.
[1913 Webster]
Men . . . often barn up the chaff, and burn up the
grain. --Fuller.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Barn \Barn\, n.
A child. See Bairn. [Obs.]
[1913 Webster]
From Jargon File (4.4.4, 14 Aug 2003) [jargon]:
barn
n.
[uncommon; prob. from the nuclear military] An unexpectedly large
quantity of something: a unit of measurement. "Why is /var/adm taking
up so much space?" "The logs have grown to several barns." The source
of this is clear: when physicists were first studying nuclear
interactions, the probability was thought to be proportional to the
cross-sectional area of the nucleus (this probability is still called
the cross-section). Upon experimenting, they discovered the
interactions were far more probable than expected; the nuclei were
"as big as a barn". The units for cross-sections were christened
Barns, (10^-24 cm^2) and the book containing cross-sections has a
picture of a barn on the cover.