noun an??dro??stene??di??one \??an-dr??-??st??n-??d??-????n, -??st??n-d??-????n\Medical Definition of ANDROSTENEDIONE: a steroid sex hormone C19H26O2 that is secreted by the testes, ovaries, and adrenal cortex and is a precursor of testosterone and estrogen Learn More About Dictionary: Definition of androstenedione