Etimology
From on + to, after into. Compare Saterland Frisian antou (“up to”).
preposition
onto
Arriving upon or on top of (speaking of a physical or metaphorical movement).
(informal) Aware of.
(mathematics) Being an onto function with a codomain of (see below).
Examples
My cat just jumped onto the keyboard.
Private-equity nabobs bristle at being dubbed mere financiers. Piling debt onto companies’ balance-sheets is only a small part of what leveraged buy-outs are about, they insist. Improving the workings of the businesses they take over is just as core to their calling, if not more so. Much of their pleading is public-relations bluster.
The thought-police were onto my plans of world domination.
The exponential function maps the set of real numbers onto the set of positive real numbers.
adjective
onto (not comparable)
(mathematics, of a function) Assuming each of the values in its codomain; having its range equal to its codomain.
Examples
Considered as a function on the real numbers, the exponential function is not onto.
Related words
synonyms
(mathematics): surjective