- Onto is defined as to or upon.
An example of onto is someone jumping from the top of one rock to another.
- to and upon; to a position on
- ☆ Slang aware of or familiar with, esp. aware of the real nature or meaning of: they're onto our schemes
- On top of; to a position on; upon: The dog jumped onto the chair.
- Informal Fully aware of; informed about: The police are onto the robbers' plans.
Of, relating to, or being a function such that every element of the codomain is the value that corresponds to an element in the domain.
- Existence; being: ontology.
- Organism: ontogeny.
Origin of onto-Late Greek, from Greek ōn, ont-, present participle of einai, to be; see es- in Indo-European roots.