I. noun — [ mass noun] 1.
[Physiology] the death of cells which occurs as a normal and controlled part of an organism’s growth or development.Also called programmed cell death.
II. derivatives apoptotic /ˌapə(p)ˈtɒtɪk / adjective
– origin 1970s: from Greek apoptōsis ‘falling off’, from apo ‘from’ + ptōsis ‘falling, a fall’.