a b c d e f g h i j k l m n o p q r s t u v w x y zu-, ubd, ube, ubergeek, uce, udp, un*x, undefined external reference, under the hood, undocumented feature, uninteresting, unix, unix brain damage, unix conspiracy, unix weenie, unixism, unswizzle, unwind the stack, unwind-protect, up, upload, upstream, upthread, uptime, urchin, url, usenet, usenet death penalty, user, user-friendly, user-obsequious, userland, utah teapot, the, utsl, uuoc