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.
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