formulation, preparation - a substance prepared according to a formula

symptom - (medicine) any sensation or change in bodily function that is experienced by a patient and is associated with a particular disease

diffuse nebula, gaseous nebula - a cluster of stars within an intricate cloud of gas and dust

planetary nebula - a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star

cloud - any collection of particles (e.g., smoke or dust) or gases that is visible

maculation, patch, speckle, dapple, fleck, spot - a small contrasting part of something; "a bald spot"; "a leopard's spots"; "a patch of clouds"; "patches of thin ice"; "a fleck of red"

pathology - the branch of medical science that studies the causes and nature and effects of diseases