Pyro- \Pyro-\, Pyr- \Pyr-\ . [Gr. ?, ?, fire.] Combining forms designating fire or heat; specifically (Chem.), used to imply an actual or theoretical derivative by the action of heat; as in pyrophosphoric, pyrosulphuric, pyrotartaric, pyrotungstic, etc. [1913 Webster]
Pyro \Py"ro\, n. (Photog.) Abbreviation of pyrogallic acid. [Colloq.] [1913 Webster]