[on-too, awn-; unstressed on-tuh, awn-]


to a place or position on; upon; on: to get onto a horse.
Informal. in or into a state of awareness about: I'm onto your scheme.


Also surjective. Mathematics. pertaining to a function or map from one set to another set, the range of which is the entire second set.

Origin of onto

First recorded in 1575–85; on + to
Can be confusedon onto on to


a combining form meaning “being,” used in the formation of compound words: ontogeny.
Also especially before a vowel, ont-.

Origin of onto-

< New Latin < Greek ont- (stem of ón, neuter present participle of eînai to be) + -o- -o-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for onto

Contemporary Examples of onto

Historical Examples of onto

  • He tossed them onto the table, and Hal Dozier rolled his smoke in silence.

  • If you'd been onto your job, things would have been smooth as silk.

  • But it must be something new, or we should have got onto it.

    It Happened in Egypt

    C. N. Williamson

  • With a word of farewell, he climbed out of the cockpit and onto a wing.

    The Solar Magnet

    Sterner St. Paul Meek

  • I can mention his name now without Ketury's landin' onto me like a snowslide.

    Cy Whittaker's Place

    Joseph C. Lincoln

British Dictionary definitions for onto


on to


to a position that is onstep onto the train as it passes
having become aware of (something illicit or secret)the police are onto us
into contact withget onto the factory


Onto is now generally accepted as a word in its own right. On to is still used, however, where on is considered to be part of the verb: he moved on to a different town as contrasted with he jumped onto the stage


combining form

existence or beingontogeny; ontology

Word Origin for onto-

from Late Greek, from ōn (stem ont-) being, present participle of einai to be
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for onto

1580s, as on to, from on + to. Appeared much later than parallel into. As a closed compound (on analogy of into), first recorded 1715.


word-forming element meaning "a being, individual; being, existence," from Greek onto-, from stem of on (genitive ontos) "being," neuter present participle of einai "to be" (see essence).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for onto



Organism; being:ontogeny.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.