• oyrogen,
• lyrogen,
• -yrogen,
• 0yrogen,
• ptrogen,
• pgrogen,
• phrogen,
• purogen,
• p7rogen,
• p6rogen,
• pyeogen,
• pydogen,
• pyfogen,
• pytogen,
• py5ogen,
• pyrogren,
• pyrogeen,
• pyrogenn,
• pyrogene,
• Pyregen

• progeny,
• pyrogenic,
• pyroxene,
• pyrogenous,
• progenitor.

The adjective form of "pyrogen" is "pyrogenic".

The plural of the "pyrogen" can be the "pyrogens".

The singular of the "pyrogen" can be the "pyrogen".