I think I know what you are alluding to, but if I am correct, you have an error in your statement.
On Gor, a Tarn is a large raptor that is used by warriors as a means of transport and combat. Sort of like a living fighter jet.
If you meant "Tarl's woman of Gor", that would be more accurate, as Tarl Cabot was the protagonist of most of the Gor books. But you would have to be more specific as to which of his women it was, as he had a long list.
I cannot believe I actually posted any of this. In my defense, I last read any of the Gor books over a decade ago. I just have a good memory for useless crap.