automagically

(AUTOmatic and MAGIC) A humorous play on the word "automatic." The automatic capabilities of many electronic and computer-oriented devices is magic to many people. In fact, the internal workings of the chip are "automagic" even to those who designed it. Automagic and automagically are also often used to avoid answering a technical question in detail.

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Automatically, but in a way that, for some reason (typically because it is too complicated, or too ugly, or perhaps even too trivial), the speaker doesn't feel like explaining to you. See magic. “The C-INTERCAL compiler generates C, then automagically invokes cc(1) to produce an executable.”

This term is quite old, going back at least to the mid-70s in jargon and probably much earlier. The word ‘automagic’ occurred in advertising (for a shirt-ironing gadget) as far back as the late 1940s.