$\begingroup$ Other symbols I have seen used for "is defined to be equal to" are three horizontal lines instead of two, and $=$ with either a triangle or "def" written directly above it. I have seen variants of these used by people who predate widespread knowledge of computer programming. It would be interesting to know the earliest uses of a special symbol for this (and what symbols …

Feb 25, 2020 · LMK is pretty well common knowledge and a popular phrase you'll likely hear spoken in face-to-face conversations. It's essentially a request for information from someone, typically whenever they might be ready to provide that information in the future.