1. That cannot be explained.

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

• inexplicible,
• inexplanable,
• inexpicable,
• unexplicably,
• inexplainable,
• unexplicable,
• unexplinable,
• inexplicibly,
• inexplicabley,
• inecplicably,
• inexplcably,
• innexplicably,
• inexpliable,
• insxplicable,
• inexsplicable,
• inexplicabble,
• inexpliate,
• Inespicable,
• inexpliciable,
• inssplicable

• inexpungeable,
• inexpugnable,
• inexplicit,
• inexpiable,
• inexpungible,
• inexplicitness,
• inseparably,
• inexpressible,
• inseparable.

The adjective form of the word "inexplicable" is "inexplicable".

The plural form of the word "inexplicable" is "inexplicables".

The singular form of the word "inexplicable" is "inexplicability"