Irrational and annoying autocorrect.

[echt]

I use word on a Mac. For no reason whatsoever, it corrects "to" into "ot", which isn't even a word as far as I know.

How can I stop this?

Try File - Options - Proofing - Autocorrect Options.

Type in "to" in the "Replace" box (or scroll through) and see if anything comes up.

If not, use that option to replace "ot" with "to". (Probably send Word into a tailspin, though.)