• bi-hard,
• mi-hard,
• ji-hard,
• hi-hard,
• nu-hard,
• nj-hard,
• nk-hard,
• no-hard,
• n9-hard,
• n8-hard,
• ni0hard,
• niphard,
• ni-gard,
• ni-bard,
• ni-nard,
• ni-jard,
• ni-uard,
• ni-yard,
• ni-hzrd,
• ni-hsrd

The adjective form of the word "ni-hard" is "ni-hardened".

The plural form of the word "ni-hard" is also "ni-hard". The term "ni-hard" is typically used as a collective noun, and it does not change when referring to multiple items of the same material.

The singular form of the word "ni-hard" is "ni-hard". The term "ni-hard" is primarily used as a collective noun or as an adjective to describe a specific type of wear-resistant cast iron alloy. It does not have a commonly used singular form.