background
n.,adj.,vt. To do a task `in background' is to do it whenever {foreground} matters are not claiming your undivided attention, and `to background' something means to relegate it to a lower priority. "For now, we'll just print a list of nodes and links; I'm working on the graph-printing problem in background." Note that this implies ongoing activity but at a reduced level or in spare time, in contrast to mainstream `back burner' (which connotes benign neglect until some future resumption of activity). Some people prefer to use the term for processing that they have queued up for their unconscious minds (a tack that one can often fruitfully take upon encountering an obstacle in creative work). Compare {amp off}, {slopsucker}.
Technically, a task running in background is detached from the terminal where it was started (and often running at a lower priority); oppose {foreground}. Nowadays this term is primarily associated with {{UNIX}}, but it appears to have been first used in this sense on OS/360.
backspace and overstrike
interj. Whoa! Back up. Used to suggest that someone just said or did something wrong. Common among APL programmers.
backward combatability
/bak'w*rd k*m-bat'*-bil'*-tee/ [from `backward compatibility'] n. A property of hardware or software revisions in which previous protocols, formats, and layouts are discarded in favor of `new and improved' protocols, formats, and layouts. Occurs usually when making the transition between major releases. When the change is so drastic that the old formats are not retained in the new version, it is said to be `backward combatable'. See {flag day}.