borrowed from French spéléologie, earlier spélæologie, from Greek spḗlaion "cave, cavern" (derivative of a base spēl-, whence also spêlynx "cave," probably of pre-Indo-European origin) + French -o--o- + -logie-logy
French spéléologie and spélæologie are closely associated with the French attorney and caving pioneer Édouard-Alfred Martel (1859-1938), who used the word on a number of occasions in the 1890's (as, for example, in "La spélæologie," Association française pour l'avancement des sciences, Compte rendu de la 22me session, Besançon, 1893, Seconde partie [Paris, 1894], pp. 886-94). In a footnote to the etymology of the word, however, Martel credits its coinage to the physician and paleoanthropologist Émile Rivière (1835-1922), noting also that "the simpler word speology has also been proposed (L. de Nussac, Essai de spéologie, Brive, in 8o, 1892): more harmonious, it is less exact, as the Greeks designated with [Greek letters] spéos the artificial cavities of tombs or Egyptian temples (spéos of Isamboul [Abu Simbel], of Beni Hasan, etc.)" ("On a proposé aussi le mot plus simple de spéologie (L. de Nussac, Essai de spéologie, Brive, in 8o, 1892): plus harmonieux, il est moins exact, car les Grecs désignaient par spéos les excavations artificielles des tombes ou temples égyptiens (spéos d'Ipsamboul, de Béni Hasan, etc.)") (Les abîmes, Paris, 1894, p. 1). It has been plausibly suggested that Ancient Greek spḗlaion may have been formed from the base of spêlynx on the model of hypógeion, hypógaion "underground chamber" (see hypogeal). Formed with the same suffix and semantically akin to spêlynx are sêranx "cavity hollowed by water," pháranx "cleft, ravine," phárynx "throat, pharynx," lárynx "larynx"—all most likely substratal words (see note at pharynx). Obscurely akin to spêlynx, etc., is spéos (neuter s-stem) "grotto, cave," which, pace Martel, is a mainly Homeric word not usually used for man-made cavities.