This has been bugging me for a while, now. What is the plural of Genius?

Many will say "geniuses", but that would be (or should be) grammatically incorrect.

At first, I naturally assumed that the plural is derived in the same way as to a word originating from Latin ending in -us.

cactus -> cactii
hippopotamus -> hippopotamii

I quickly ran into a problem: If this is applied to genius, then we get geniii. Half that word is a row of Is... highly unlikely that that's right.

So I must ask; what the hell is the plural of genius?

Yes, I may have too much time on my hands.
Quote by SpartanTHC

The genius possesses something?

Quote by Jaymz_515
I think geniuses is the preferred option these days.

Probably. I think you'd get funny looks if you applied the correct Latin one, whatever it is.
Fool, you only add one 'i'.

Cacti, genii.
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Quote by jaffawoman
Fool, you only add one 'i'.

Cacti, genii.

In the states, maybe. But you guys spell 'colour' as 'color'. In Britain '-us' becomes '-ii', as far as I'm aware.