1. That cannot be pierced.

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

• ynpierceable,
• hnpierceable,
• jnpierceable,
• 8npierceable,
• 7npierceable,
• ubpierceable,
• ujpierceable,
• uhpierceable,
• unoierceable,
• unlierceable,
• un-ierceable,
• un0ierceable,
• unpuerceable,
• unpjerceable,
• unpkerceable,
• unpoerceable,
• unp9erceable,
• unp8erceable,
• unpiwrceable,
• unpisrceable

• impenetrable,
• imperceptible,
• insurmountable,
• indestructible,
• inviolable,
• unfathomable,
• inaccessible,
• incomprehensible,
• unbreakable,
• insusceptible.

The adjective form of the word "unpierceable" is "unpierceable" itself.

The plural form of the word "unpierceable" is "unpierceables".

The singular form of the word "unpierceable" is "unpierceable". It does not change in the singular form.