(1):

(n.) That form of reproduction which requires but one parent, as in reproduction by fission or in the formation of buds, etc., which drop off and form new individuals; asexual reproduction.

(2):

(n.) Oneness of origin; esp. (Biol.), development of all beings in the universe from a single cell; - opposed to polygenesis. Called also monism.

(3):

(n.) The direct development of an embryo, without metamorphosis, into an organism similar to the parent organism; - opposed to metagenesis.