'Pyr-' definitions:

Definition of 'Pyr-'

From: GCIDE

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]