D defs.my
Entry 1 sense Webster, 1913

Pyrophorus

· Py·roph·o·rus · IPA
01 n. Any one of several substances or mixtures which phosphoresce or ignite spontaneously on exposure to air, as a heated mixture of alum, potas…
  1. 1.
    Any one of several substances or mixtures which phosphoresce or ignite spontaneously on exposure to air, as a heated mixture of alum, potash, and charcoal, or a mixture of charcoal and finely divided lead.(Old Chem.)