1. Unfitness.

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

• eneptness,
• unaptness,
• jnaptness,
• knaptness,
• onaptness,
• inapness,
• inaptnes,
• innaptness,
• inapptness,
• inappness,
• intactness,
• unaptnesse,
• unaptnes,
• unapptness,
• inaptnessses,
• inappotness,
• inapatness,
• inaptestt,
• inapitest,
• snapyness

• ineptness,
• infatuate,
• inhabit,
• inpatient,
• inaptitude,
• invade.

The adjective form of the word "inaptness" is "inapt".

The plural of the "inaptness" can be the "inaptnesses".

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