1. That which stiffens.

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

• stiffnes,
• stiffners,
• stiffned,
• stiffined,
• stifened,
• stiffend,
• stiffner,
• stifeners,
• atiffener,
• ztiffener,
• xtiffener,
• dtiffener,
• etiffener,
• wtiffener,
• stifferner,
• stiffenerr,
• stifener,
• stiffaner,
• stiffter,
• stippender

• stuffiness,
• Steven,
• stiffening,
• Steffan,
• steffensen,
• stiffen,
• stiffened,
• stiffness,
• Steffen,
• Stefan,
• Steffenson,
• steffens,
• Steffenhagen.

The adjective form of the word "stiffener" is "stiffening".

The plural of the "stiffener" can be the "stiffeners".

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