1. Invalidity.

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

• unvalidness,
• jnvalidness,
• knvalidness,
• onvalidness,
• 9nvalidness,
• 8nvalidness,
• ibvalidness,
• imvalidness,
• ijvalidness,
• ihvalidness,
• incalidness,
• inbalidness,
• ingalidness,
• infalidness,
• invzlidness,
• invalidnes,
• invaladness,
• invaladnes,
• invaladidness,
• invaledness

• invalidation,
• invalidate,
• invalidity,
• invalidating,
• invalidator,
• invalidated,
• invaluableness,
• invalidism.

The adjective form of the word "invalidness" is "invalid".

The plural of the "invalidness" can be the "invalidnesses".

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