A ribosyl derivative of adenine, isolated from the fungus Clitocybe nebularis, which has antibiotic properties and can act as a nucleoside analogue; 9-β- d -ribofuranosyl-9 H -purine, C₁₀ H₁₂ N₄ O₄.
1940s. From scientific Latin nebularis, specific epithet of the fungus Clitocybe nebularis (formerly Agaricus nebularis) (A. J. G. C. Batsch Elenchus Fungorumi. xxviii. 122; from classical Latin nebula + -āris) + -ine.