1. of or relating to or resembling a nebula - the nebular hypothesis of the origin of the solar system • Syn: nebulous • Pertains to noun: nebula (for: nebulous), nebula • Derivationally related forms: nebula (for: nebulous), nebula • Topics: astronomy, uranology 2. resembling a cloud • Syn: cloudlike • Similar to: cloudy • Derivationally related forms: nebula