1. That cannot be described.

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

• undescribeable,
• undescriable,
• undescribible,
• undescrible,
• uindescribable,
• indescribable,
• undestroyable,
• 7ndescribable,
• ubdescribable,
• umdescribable,
• ujdescribable,
• uhdescribable,
• unsescribable,
• unxescribable,
• uncescribable,
• unfescribable,
• undescrivable,
• undercribable,
• unrespriable,
• unasbcribable

• undesirable,
• undescriptive,
• undesirably,
• undiscoverable,
• undestroyable.

The adjective form of the word "undescribable" is "indescribable".

The plural form of the word "undescribable" is "undescribables".

The singular form of the word "undescribable" is "undescribable". The word itself is an adjective that does not change in form whether used in the singular or plural.