Biennial and biannual are amongst those confusing words in the English language, up there with affect and effect.
I’ll let our trusty Collins dictionary explain:
So, to be clear, the Muster happens biennially – every two years.
This is a trial by DoC now that the numbers of horses in the ranges are down in the three hundreds. It is also the reason why we are expecting a muster of 170+ horses.
Importantly, if you are wanting a horse from a muster, act now! There won’t be another one until 2014. We would hate for the confusion to mean that you have missed out.
Please excuse us when we, and the press, slip up on our English.
I think I will try to use both words in my conversations today.