I wonder if a lot of Americans spell mandatory wrong? They tend to say man-dit-ory and I’m guessing a lot of them try to spell it that way. I must confess that I thought there might be a variant spelling using the ‘i’, as sometimes crops up when the two languages continue to diverge, but no, the ‘i’ version is a non-runner.

It’s easier for us European English speakers to spell it correctly since we sound the word differently to our new world friends. For us the second syllable is the gloriously named ‘schwa‘ vowel, the sound we make on many unaccented syllables that comes from the middle of our mouth, the most economical and efficient place from which to issue a non-stressed syllable. Think of the word ‘sofa’, and the ‘a’ is your classic schwa sound.

This, I would suspect, makes it more natural for us to guess that an ‘a’ is the correct letter, since it feels closer than an ‘i’ and certainly better than an ‘e’, ‘o’ or ‘u’, although they all have schwa representation as well – as in independent, potential and support, respectively.

I guess you can make the argument that since you ‘mandate’ something, it would make sense to see mandatory, but I’m going to stick my neck out and say don’t be surprised if US dictionaries start permitting manditory as an alternative spelling in the next decade or so.