Isolated Pawn
A pawn with no friendly pawns on the adjacent files, unable to be defended by another pawn.
Isolated pawns are frequently structural weaknesses, since only pieces (not pawns) can defend them, but they can also provide open lines and piece activity that partly compensate for the weakness.
Etymology
Isolated is an 18th-century Frenchified word, “rendering French isolé, from Italian isolato, from Latin insulatus 'made into an island'” — so an isolated pawn is literally a pawn marooned on its own island of a file. Edward Winter's dedicated feature gives the earliest known chess occurrence: “The isolated pawn is perhaps rather more than compensated by the forwardness of the pieces,” in Studies of Chess (London, 1810), p. 208, antedating the OED's own citation from C. Pearson's Chess Exemplified (London, 1842). Staunton's 1847 glossary and Steinitz (1889) both formalise the term. The affectionate German-Italian nickname isolani is separate and later: Winter's earliest instance is Leonhardt's 1910 annotations, and in English, “White has an 'isolani'” appears in Nimzowitsch's My System (London, 1929), which Wikipedia credits with the coinage of isolani.
First documented: 1810 — Studies of Chess (London, 1810), p. 208
Translations
Translations for this term haven't been added yet.