Similarly to Latin words with no plurals in English I still have trouble with some plurals when the word ends in -us.
For example, I have often been told that the plural for cactus is cacti, but then some argue it is cactuses.
Merriam Webster states that it could be either octopuses or octopi, but then someone a while back said it is actually octopodes. Huh?
When talking about the plural for hippopotamus, is it hippopotamuses or hippopotami?
How do I tell when to use -uses rather than -i?