Onto

//ˈɔn.tu// adj, prep, slang

adj, prep, slang ·Common ·High school level

Definitions

Adjective
  1. 1
    Attaining each of the values in its codomain; having its image equal to its codomain. not-comparable

    "Considered as a function on the real numbers, the exponential function is not onto, as it never takes on values less than or equal to zero."

Preposition
  1. 1
    Arriving upon or on top of (speaking of a physical or metaphorical movement).

    "My cat just jumped onto the keyboard."

  2. 2
    Aware of. informal

    "The thought-police were onto my plans of world domination."

  3. 3
    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."

Synonyms

All synonyms
atopone to oneoverright totalsurjectivesurjective

Example

More examples

"Try as you might, but you cannot force a belief onto someone else, much less your own self."

Etymology

From on + to, after into. Compare Saterland Frisian antou (“up to”).

Related phrases

back ontobe ontobe onto somethingcall onto the carpetclock ontocome ontocop ontocotton ontocrack ontofreeze ontoget ontoglom onto

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.