H.W. Fowler refers in Modern English Usage to the ‘misshapen brood’ of bi– words that are used to describe the frequency of intervals: biannual, bi-monthly, bi-weekly and the like.
The problem with them is that they are ambiguous: bi-weekly, for example, can mean either twice a week or every two weeks. At least a biennial (like the Biennale art exhibition held in Venice) is always held every two years, not twice in one.
Careful drafters of contracts will obviously want to make things perfectly clear, especially when dealing with dates of payment obligations and the like. And even non-contractual writers may wish to avoid uncertainty.
There are some options to avoid the ambiguity of bi–. Semi-monthly is clearer than bi-monthly, if you want to say that something is to occur twice in any given month. But both words are what Fowler calls ‘ugly hybrids’. Fortnightly is an option, if you’re OK with sounding very British. Or you could just say twice monthly, every two weeks or every other week. Fowler’s proposal to adopt half-monthly doesn’t appear to have gained much traction, but you could try it – and you wouldn’t be misunderstood.
If you’re old enough, you’ll remember Canada’s centennial in 1967 and the bicentennial of US independence in 1976. In the UK, these would have been centenary (pronounced cen-TEEN-er-ee) and bicentenary (bye-cen-TEEN-er-ee).
When Toronto celebrated the 150th anniversary of its incorporation back in 1984, someone dredged up sesquicentennial, a word that doesn’t appear to be used all that much. It did engender a twee squirrel mascot called Seskwee (although it wasn’t black in colour like the characteristic Toronto rodent).
The federal government, wisely, did not try to figure out the Latinate term for the 125th anniversary of Confederation when that occurred in 1992. (The unwieldy quasquicentennial has been suggested.) Instead, the feds opted for Canada 125, universally called Canada one two five (perhaps a deliberate echo of the colloquial term for a case of beer). Canada 125 made up in clarity what it lacked in imagination – and, predictably, we are approaching what is officially being called Canada 150.
But perhaps we still have the dodransbicentennial, dodrabicentennial or possibly dequabicentennial of Confederation to look forward to in 2042 – with Dodra or Dequa the beaver as mascot?
Once every thousand years. Also, now, used to refer to the much-maligned generation that came of age around the dawn of the new millennium – although millennial is often used for anyone born somewhere between the early 1980s and the early 2000s.
Note: spell millennial and millennium with two Ls and two Ns. Millennia (and centuries) begin in years ending in 1 (2001, not 2000), by the bye; there was no year 0.
Next: keep your cultural references current and universal