I was wondering this morning why we say once and twice as alternatives to one time and two times in English.

It’s one of these things learners of English find it hard to remember to use. Partly it’s because there’s no greater pattern at work, as for every other number after one and two we just say three times, four times etc. It’s also because most other languages use the equivalent of one time and two times.

So why does English have to be awkward, once again, and not just use one time and two times?

It all goes back to Middle English, and the word ones. This was the genitive case of the word on, meaning one. A genitive case in linguistics marks a word modifying another one (both usually being nouns), usually referring to some relationship between the two. This could be a relationship of possession, for example. Modern English strictly doesn’t have a genitive case, but the use of -‘s to denote possession is a relic of the Old English use of S as a suffix in the genitive case. This is also evident in words like yours, hers, his (from hes), and adverbs like afterwards, towards, backwards etc.

As you can see from these examples, the genitive case is broader than just referring to possession. It could be used in an adverbial sense too, and this is what we see in once and twice, meaning one time or two times.

And of course there was thrice, with a similar etymology, meaning three times, but that’s largely old-fashioned now, except in Indian English, where it’s still pretty common.

OK, so that’s where once and twice come from, but why do we still use them? Well for one, they’re short and simple, more convenient than saying one time or two times. And we’re going to refer to things happening once or twice much more often than we’ll refer to things happening more frequently, which is why we don’t need short forms for numbers any higher, and why thrice has now largely fallen out of favour.

And most importantly, could you imagine a song called “One Time, Two Times, Three Times a Lady?” It wouldn’t be catchy at all!