Fortnightly

What does biweekly mean to you? How about bimonthly or biannually?

While each of us will have our own, perhaps unambiguous, reaction to it, the word biweekly is interpreted as "twice a week" or "once every two weeks." I know this from personal experience of confusing people en-masse. The dictionary even carefully, if unhelpfully, defines it as meaning either. It's a strange quirk of the English language. But it's so handy, what to do? An excellent, concise solution is the word fortnightly.

Fortnightly has the helpful unambiguous quality that it means "once every fortnight," so "once every two weeks." And it's also just one word. If something happens "two times a week," I think you need to spell it out or use "twice a week" or perhaps "every Monday and Thursday." Or perhaps semi-weekly might give you some mileage.

The same source of confusion applies to the words bimonthly and biannually—to be sure of being understood correctly, it's best to avoid them. Phrases like "every second month," "every two months," "twice a month," or "two times each year" are helpful here.

Ambiguity in how we talk about time is also illustrated in some of my favourite research done by Lera Boroditsky. For example, if I say, "The meeting on Wednesday has been moved forward by two days," when is the meeting now? It turns out that people are split on whether the meeting is now on Monday or on Friday. And I remember a fascinating example of the Kuuk Thayore aboriginal people in Australia who don't use words like left and right, and instead, always use the cardinal directions like north, south, east and west—"Oh, there's an ant on your southwest leg". There's a taster in her talk, How Language Shapes the Way we Think.