Equivocal

Equivocal is Latin for what in Greek would be homonym.

Both refer to cases where one word is used in two different meanings.

To use a term equivocally, is to (grammatically) use it in more than one meaning. and even courts have occasionally done so in dubious ways.

Equivocation usually refers to a logical argument that uses words equivocally - usually making that argument fallacious.