Weak Square
A square that cannot be defended by a pawn and is therefore vulnerable to permanent occupation by an enemy piece.
Weak squares, especially of the color a player's own bishop does not control, can become long-term liabilities that an opponent exploits for the rest of the game.
Etymology
This is one of the few strategic terms with a clean, self-documented coinage. In The Modern Chess Instructor (New York, 1889), Wilhelm Steinitz introduces the pair of terms “a hole” and “weak square,” then dates his own coinage explicitly: “The latter term, which is now generally accepted as a technical definition, was first used by the author in The International Chess Magazine of November 1886, where the disadvantage which it is intended to describe was also first pointed out.” The metaphor is architectural rather than martial: a gap in a pawn wall that cannot be patched, because only a pawn could cover the square and no pawn can ever reach it. Capablanca carried the term forward, heading section 33 of Chess Fundamentals (1921) “The Influence of a 'Hole.'”
First documented: 1886 — Wilhelm Steinitz, The International Chess Magazine, November 1886 (as stated by Steinitz himself in The Modern Chess Instructor, 1889)
Translations
Translations for this term haven't been added yet.