Opening Theory

Opening theory is a compound term of art rather than an etymologically distinct word: it denotes the accumulated published analysis of opening variations. The practice long predates the phrase, beginning with the manuscripts and books of Lucena in 1497, Damiano in 1512 and Ruy Lopez in 1561. Wikipedia records that opening theory was studied more scientifically from the 1840s on, which is the period in which the modern notion of a shared, published, continually revised body of opening knowledge takes shape. The vocabulary that surrounds it, such as book and out of book for moves inside or outside published theory, and theoretical novelty for a new move in a known position, is part of the same conceptual family. FIDE issued a standardising booklet of opening names in 1933 and the Encyclopaedia of Chess Openings later codified the whole field into 500 codes. No source located in this session gives a first documented year for the phrase itself.

First documented: n.a. — n.a. for the phrase; the earliest surviving systematic opening analysis is Lucena (1497), and Wikipedia dates scientific study of opening theory from the 1840s on