anvil \an"vil\, n. oe. anvelt, anfelt, anefelt, as. anfilt,
   onfilt; of uncertain origin; cf. ohg. anafalz, d. aanbeld.
   1. an iron block, usually with a steel face, upon which
      metals are hammered and shaped.
      1913 webster

   2. anything resembling an anvil in shape or use. specifically
      anat., the incus. see incus.
      1913 webster

   to be on the anvil, to be in a state of discussion,
      formation, or preparation, as when a scheme or measure is
      forming, but not matured. --swift.
      1913 webster
see also:
incus to be on the anvil