1. The loss of vitality in or the degeneration of certain cells or tissues, as in the aging process; physical degeneration; loss of vitality: "The degeneration or loss of function or vitality in an organism or in cells or tissues not due to any apparent injury; such as, senile dementia and related abiotrophies."
2. Progressive loss of vitality of certain tissues or organs leading to disorders or loss of function: "The abiotrophy of the heart may be appreciably shorter than that of other organs of the body, leading to early disturbance in function that upsets organ-equilibrium."