In common use, I think both are correct, at least in an English speaking kitchen. The context deciding it.
We were taught that Fond and Stock were synonymous. Fond blanc, Fond Brun, Fond de volaille, Fond de poisson and Fond de legumes were the basic stocks. Fonds de braise was the leftovers at the bottom of the braising pot.
I don't recall ever seeing the word "Sucs" used anywhere. It's not in the index to my 1969 English translated Escoffier.