1. A gem, such as a diamond, that is set alone.
2. Games. Any of a number of card games played by one person.
3. Any of several thrushes of the genus Myadestes, found in North and Central America and noted for their beautiful song.
4. Either of two large flightless birds (Raphus solitarius and Pezophaps solitaria) of the Mascarene Islands which together with the dodo make up the extinct family Raphidae. The solitaires were extinct by the end of the 18th century.

[French, solitary, from Old French. See solitary.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.