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.