Know why cattywampus was trending last week?
early 15c., from be- intensive prefix + have in sense of "to have or bear (oneself) in a particular way, comport" (cf. German sich behaben, French se porter). Cognate Old English compound behabban meant "to contain," and alternatively the modern sense of behave might have evolved from behabban via a notion of "self-restraint." Related: Behaved; behaving.
1. [primarily MS-DOS] Said of software conforming to system interface guidelines and standards. Well-behaved software uses the operating system to do chores such as keyboard input, allocating memory and drawing graphics. Oppose ill-behaved.
2. Software that does its job quietly and without counterintuitive effects. Especially said of software having an interface spec sufficiently simple and well-defined that it can be used as a tool by other software. See cat.