cotwin

Etymology

From co- + twin.

cotwin means A twin's twin. Lexicurio rates it Sui generis — a strength score of 86 out of 100.

noun

A twin's twin.“In contrast, if a psychopathologic feature is acquired as a result of an environmental factor unique to the exposed twin, eg, the traumatic event, their cotwins should not have an increased incidence of the feature.”