In obsolete|lang=en terms the difference between foil and foinery

is that foil is (obsolete) to defile; to soil while foinery is (obsolete) thrusting with the foil; fencing with the point of the sword, as distinguished from broadsword play.

As nouns the difference between foil and foinery

is that foil is a very thin sheet of metal or foil can be failure when on the point of attainment; defeat; frustration; miscarriage or foil can be (hunting) the track of an animal while foinery is (obsolete) thrusting with the foil; fencing with the point of the sword, as distinguished from broadsword play.

As a verb foil

is to prevent (something) from being accomplished or foil can be (mathematics) to multiply two binomials together or foil can be (obsolete) to defile; to soil.