Solitaire (noun)

1. A card game played by one person.
2. A ring or other piece of jewelry that has a single stone or other decorative element.
3. A person who lives alone, a solitary.

Origin:

From french solitaire, from old french solitair, from latin solitarius ("lonely, solitary"), from solus ("alon.e")

Examples:

1. He passed the time by playing solitaire on his computer.
2. She was wearing a beautiful diamond solitaire ring.
3. The solitaire was a symbol of her independence.
4. He was a solitaire, preferring to spend his time alone.
5. The solitaire was a solitary figure, always alone and distant.