pernicious anemia: a chronic progressive anemia of older adults; thought to result from a lack of intrinsic factor (a substance secreted by the stomach that is responsible for the absorption of vitamin B12)
abstraction: a general concept formed by extracting common features from specific examples
ginkgoales: coextensive with the family Ginkgoaceae: plants that first appeared in the Permian and now represented by a single surviving species; often included in Coniferales