clockwork: any mechanism of geared wheels that is driven by a coiled spring; resembles the works of a mechanical clock
physical entity: an entity that has physical existence
erythroblastosis fetalis: severe anemia in newborn babies; the result of Rh incompatibility between maternal and fetal blood; typically occurs when the child of an Rh-negative mother inherits Rh-positive blood from the father; can be diagnosed before birth by amniocentesis