onto-

1. a combining form meaning “being,” used in the formation of compound words: ontogeny.

combining form

1. existence or beingontogeny; ontology

word-forming element meaning “a being, individual; being, existence,” from Greek onto-, from stem of on (genitive ontos) “being,” neuter present participle of einai “to be” (see essence). pref.

1. Organism; being:ontogeny.