Foley is named after Jack Foley. When you use Foley in a sentence, be sure to captiablize it, pro's are fuzzy about this. And, the Foley Police will take you away if you don't :)
Advise from a PRO:
Sound FX are not Foley.
Only sounds recorded live to picture are Foley. 99% of the sound FX in a film are not Foley, they are ... sound FX.