What is the meaning of root word sol in solitaire?

The word "solitaire" comes from the French word "solitaire," which itself is derived from the Latin word "solus," meaning "alone" or "single".

Therefore, the root word "sol" in "solitaire" doesn't directly refer to the sun, as you might expect. It instead reflects the game's nature as a one-player game, where you are playing alone.