1. He who or that which hardens.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• hardend,
• haddened,
• hardners,
• partener,
• hardere,
• hardeer,
• hardine,
• harderned,
• garderner,
• hardned,
• gardenier,
• harpener,
• hardder,
• hadened,
• bartener,
• hardnes,
• hardwer,
• haedened,
• hardner,
• laecener

• harden,
• gardener,
• hardened,
• hardier,
• harder,
• hardens.

The plural of the "Hardener" can be the "hardeners".

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