Is "swop" an acceptable variant of "swap"?

I've always spelt it with an "a". But my friend insists on spelling it with an "o". Is this an acceptable variant?


Solution 1:

In American English and British English swop is a variant spelling of swap. (See the also swop note at the top of the page.)

The copy of the NOAD I had on my Mac Mini explicitly said swop is a variant spelling of swap, and also reported swop as chiefly British.

Solution 2:

I know that "swop" is a variant, having seen it in manuals and help discussions like this, but I've never seen it used in real life (i.e., in US usage). Looks very UK-ish.