What is the right definition of agnostic?

[Angrboda]

T.H. Huxley introduced a definition of agnosticism in the 19th century. His agnosticism was that neither the existence nor non-existence of God could ultimately be known, and that positions on the topic were akin to groundless speculation. That's one take on the term. Another take is that given by Robvalue above, that agnosticism has to do only with knowledge and not belief. Both usages have historical and contemporary justifications, so neither is more right than the other. What's important is simply to be clear which usage one has in mind when someone else uses the term, and being open to both uses.

https://philosophynow.org/issues/99/Huxleys_Agnosticism