|a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.|
|a chattering or flighty, light-headed person.|
|apoptosis (āp'əp-tō'sĭs, āp'ə-tō'-) Pronunciation Key
A natural process of self-destruction in certain cells, such as epithelial cells and erythrocytes, that are genetically programmed to have a limited life span or are damaged. Apoptosis can be induced either by a stimulus, such as irradiation or toxic drugs, or by removal of a repressor agent. The cells disintegrate into membrane-bound particles that are then eliminated by phagocytosis. Also called programmed cell death.
The programmed death of a cell. Scientists believe that this process is governed by chemical signals a given cell receives from its neighbors.