sole

Sole is a term with several distinct meanings in English, including a type of fish, the underside of the human foot or a shoe, and the sense of being the only one. The word derives from the Latin solus, meaning alone or single.

In ichthyology, sole refers to various flatfishes that inhabit coastal and shelf waters. True soles are in the genus Solea and related genera within the family Soleidae, with Solea solea (the common sole) among the best known species in European waters. Other fish marketed as “sole” include species from different genera or regions, such as the Pacific Dover sole (Microstomus pacificus), which demonstrates regional variation in common naming. Soles are demersal, living near the seabed, and have a laterally compressed body with eyes on one side. Their flesh is pale and prized in cooking; classic preparations include sole meunière. In markets, the label “sole” may refer to fillets from several different flatfish, depending on regional naming conventions.

Anatomically, the sole is the bottom surface of the foot, extending from the heel to the toes. In footwear, the sole is the bottom portion of a shoe or boot, often made of leather, rubber, or synthetic materials, and designed to provide protection, support, and traction.

As an adjective, sole means only or single, as in “the sole survivor.” This usage traces back to the same Latin root solus and is common in everyday language.