The word "sol" can refer to several things depending on the context. In music, "sol" is the fifth note of the diatonic scale in the solfège system, which is used for singing. In another context, "Sol" can refer to the sun, especially in scientific discussions or poems. In astronomy, it often describes a solar day on Mars.
The term "sol" originates from the Latin word "sol," which means "sun." The musical term is derived from the solfège system established in medieval music notation.