Time and a Half

My iPod, my nearly-constant companion, is currently feeding me a helping of Manhattan Transfer. Their "Twilight Zone/Twilight Tone" got me, naturally enough, to wondering about the word "twilight". My first thought--which I quickly discarded--was that "twi-" was somehow related to "twixt", because twilight is the light between--that is, betwixt--darkness and daylight.

Well, that's how folk etymology arises, I suppose. The truth is simultaneously simpler and more complicated: the "twi-" of "twilight" is related to the word "twelve" (which I wrote about here) and also "two". The German for "two" is "zwei", and the similarity between "zwei" and "two"/"twelve"/"twi-" is obvious.

And what does two of anything have to do with twilight? That's where it gets interesting. Prefixes of twoness in English usually serve two purposes: they can signify either "two" or "one half": "bisect" means, depending on how you look at it, "divide into two" or "divide into halves". Likewise with "biannual", which may mean either "every two years" or "twice every year", which is to say "every half-year". Some say that "biannual" ought properly to be reserved for "twice a year", with "biennial" referring to "every other year". The trouble is "biannual" has meant both things for a very long time, and it's too late to put that cat back in the bag. This is of course terribly confusing, but it has plenty of company in the language. (Some, and I count myself among their number, think it's usually best to avoid the word altogether and use "twice yearly" or "every other year", as the case may be. This solution isn't elegant, and it's a shame to lose a word, but clear expression is paramount.)

Anyway, "twilight". It doesn't mean "two lights"; it means "half-light". How unexpectedly poetic!