Mon`o*gen"e*sis (?), n. [Mono- + genesis.] 1. Oneness of origin; esp. (Biol.), development of all beings in the universe from a single cell; -- opposed to polygenesis. Called also monism. Dana. Haeckel.

2. (Biol.) 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. Haeckel.

3. (Biol.) The direct development of an embryo, without metamorphosis, into an organism similar to the parent organism; -- opposed to metagenesis. E. van Beneden.