a gem (usually a diamond) in a setting by itself
"The jeweler set the brilliant-cut solitaire into a simple platinum band, allowing its sparkle to stand alone without distraction."
extinct flightless bird related to the dodo
"The rare solitaire, an extinct flightless bird from Mauritius, once roamed the island's dense forests alongside the famous dodo."
a dull grey North American thrush noted for its beautiful song
"The solitaire sang a haunting melody that echoed through the misty mountains of Maine."
A person who lives alone; a recluse or hermit.
"After moving to the cabin in the woods, he became a true solitaire, rarely speaking to anyone except his dog."
In plain English: Solitaire is a card game you can play by yourself without needing other people to join in.
"She enjoys playing solitaire on her train ride to work every morning."
Usage: Use the noun form to describe someone who chooses isolation, while reserving the adjective for things that exist in solitude. Do not confuse this with card games unless specifically referring to single-player versions of those games.
living or being alone; solitary
"After years in the bustling city, she finally found peace living as a solitaire on her remote farm."
In plain English: Solitaire describes something that is done alone without any help from others.
"She spent her afternoon playing solitaire in front of the window."
The word solitaire was borrowed into English from the French language. It originally meant "lone" or "single," a meaning it shares with its doublet solitary.