The dark clouds gathered ominously overhead.

My friend's name is Omid.

The dark clouds and eerie silence added to the ominousness of the abandoned house.

There were several omissions in the report.

The omittance of important details in the report led to misunderstandings.

There were several omittances in the report.

He omits important details in his report.

The Greek alphabet has 24 letters, including Omikron.

Omigod, I can't believe what just happened!

She is often omissive in her emails, forgetting to include important details.