Is "ideot" a euphemistic form of idiot?

this tells you it is an obsolete form

Source

obs. stands for obsolete; what does ff. stand for?

http://public.oed.com/how-to-use-the-oed/

http://public.oed.com/how-to-use-the-oed/abbreviations/

http://public.oed.com/how-to-use-the-oed/abbreviations/#f

Good luck Walter.

Why not tell us what ff. stands for directly? Why try to beat around the bush?
No ff. entry can be found in the links you offered.