D defs.my
Entry 1 sense Webster, 1913

Pyroboric

· Pyr·o·bo·ric · IPA
01 a. Pertaining to derived from, or designating, an acid, H2B4O7 (called also tetraboric acid), which is the acid ingredient of ordinary borax, …
  1. 1.
    Pertaining to derived from, or designating, an acid, H2B4O7 (called also tetraboric acid), which is the acid ingredient of ordinary borax, and is obtained by heating boric acid.(Chem.) Also: tetraboric