4.2 /for' poynt too'/ n.

Without a prefix, this almost invariably refers to BSD Unix release 4.2. Note that it is an indication of cluelessness to say "version 4.2", and "release 4.2" is rare; the number stands on its own, or is used in the more explicit forms 4.2BSD or (less commonly) BSD 4.2. Similar remarks apply to "4.3", "4.4" and to earlier, less-widespread releases 4.1 and 2.9.

--The Jargon File version 4.3.1, ed. ESR, this entry manually entered by rootbeer277.