# onto

### adjective

1. (mathematics, of a function) Assuming each of the values in its codomain; having its range equal to its codomain.

*- Considered as a function on the real numbers, the exponential function is not onto.*

### preposition

1. Upon; on top of.

*- My cat just jumped onto the keyboard.*

2. (informal) Aware of.

*- (The thought-police were onto my plans of World domination.)*

3. (mathematics) Being an onto function with a codomain of (see below).

*- The exponential function maps the set of real numbers onto the set of positive real numbers.*