Meaning

noun a long narrow depression in a surface

noun a small opening or crevice (especially in a rock face or wall)

originFrom Middle English crany, crani (“cranny”), apparently a diminutive of *cran (+ -y), from Old French cran, cren (“notch, fissure”), a derivative of crener (“to notch, split”), from Medieval Latin crenō (“split”, verb), from Vulgar Latin *crinō (“split, break”, verb), of obscure origin. Despite a spurious use in Pliny, connection to Latin crēna is doubtful. Instead, probably of Germanic or Celtic…

Etymology from Wiktionary, CC BY-SA 3.0