So today I was doing something or other (sewing a small antique rug to a backing board, I think) and a question popped into my head: "Where does the word 'metronome' come from?"
It was completely unbidden. There weren't any pictures of metronomes nearby, I hadn't been using a metronome recently, I didn't read something about metronomes earlier in the day. It just kind of showed up. Metronome: what's the deal, brain?
I am a little bit ashamed to say that my first thought was, "Metronome. Metropolis. Hmmm. Nope, don't see the connection.*" My first thought ought to have been, "'Metr-' is clearly related to 'meter', because a metronome is a sort of measuring device." But that thought (which, by the way, is correct) took about a minute to percolate through my brain and into my consciousness.
And then I couldn't figure out the second part. What could "-nome" mean? I discarded "gnome" immediately, of course, though it was an amusing thought, given the general shape and size of a metronome. Then it occurred to me that "nomen" is the Latin word for "name", as in "nominal", which is to say "in name only". This, unfortunately, didn't make any sense; I torqued it around in my head, thinking that, well, a metronome lets you follow a time signature accurately and your signature is your name.... But I knew it was futile.
The "-nome" in "metronome", as it turns out, comes originally from an Indo-European root, "nem-", which gave English quite a few words, because it has quite a few meanings, most having to do with divisions and arrangements (as in various fields of human endeavour such as astronomy, the arrangement of the stars). And this is the key to "metronome": it's a meter--a measuring device--which divides time up for us.
*The "metr-" in "metropolis", and I did not know this until I just now looked it up, is from "mater", "mother", because a metropolis is originally a mother-city, the most important one, the one that generates the others. The "-polis" part I already knew, because it is led to such words as "politics" and "policy" and "police", without which you can't have a city, or, really, any kind of society beyond, say, a few hundred people.