Grave (noun)

1. A place where someone is buried, typically marked by a tombstone.
2. A serious or solemn expression or tone.
3. A situation that is dangerous or likely to cause problems.

Origin:

Late middle english: from old french grave, from latin sepultura "burial", from sepelire "bury".

Examples:

1. She visited her father's grave on the anniversary of his death.
2. He spoke with a grave voice.
3. The economy faces a grave threat.
4. The grave was simple, with only a small headstone.
5. She put on a grave face when she heard the news.