= U =
UBD
UN*X
undefined external reference
under the hood
undocumented feature
uninteresting
UNIX
UNIX brain damage
UNIX conspiracy
UNIX weenie
unixism
unleaded
unswizzle
unwind the stack
unwind-protect
up
upload
upthread
urchin
USENET
user
user-friendly
user-obsequious
USG UNIX
UTSL
UUCPNET