ontoprep.[On + to. Cf. Into.] On the top of; upon; on. See On to, under On, prep.()n.[See Ontology, and Genesis.] (Biol.) The history of the individual development of an organism; the sequence of events involved in the development of an organism; the history of the evolution of the germ; the development of an individual organism, -- in distinction from phylogeny, or evolution of the tribe. Called also henogenesis, henogeny.()