1 : a natural prolongation or projection from a part of an organism either animal or plant
2 : (biology) the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms
3 : (biology) the process of an individual organism growing organically; a purely biological unfolding of events involved in an organism changing gradually from a simple to a more complex level
4 : a natural prolongation or projection from a part of an organism either animal or plant
