[ on-too, awn-; unstressed on-tuh, awn- ]
/ ˈɒn tu, ˈɔn-; unstressed ˈɒn tə, ˈɔn- /


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

Definition for onto (2 of 2)


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

British Dictionary definitions for onto (1 of 2)


on to

/ (ˈɒntʊ, unstressed ˈɒntə) /


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

British Dictionary definitions for onto (2 of 2)


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

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.