< jargon > 1. A piece of hardware that encapsulates some function but can't be used without some kind of front end . Today we have, especially, " print engine ": the guts of a laser printer .
2. An analogous piece of software; notionally, one that does a lot of noisy crunching , such as a "database engine", or " search engine ".
The hackish senses of "engine" are actually close to its original, pre-Industrial-Revolution sense of a skill, clever device, or instrument (the word is cognate to "ingenuity"). This sense had not been completely eclipsed by the modern connotation of power-transducing machinery in Charles Babbage 's time, which explains why he named the stored-program computer that he designed in 1844 the " Analytical Engine ".
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