kerogenPronunciation: /ˈkɛrədʒ(ə)n/Definition of kerogen noun [mass noun] a complex fossilized organic material, found in oil shale and other sedimentary rock, which is insoluble in common organic solvents and yields petroleum products on distillation. Origin: early 20th century: from Greek kēros 'wax' + -genkerogen in other Oxford dictionaries Definition of kerogen in the US English dictionary