[ on-too, awn-; unstressed on-tuh, awn- ]
/ ˈɒn tu, ˈɔn-; unstressed ˈɒn tə, ˈɔn- /
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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.
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Origin of onto

First recorded in 1575–85; on + to


on, onto , on to

Other definitions 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. 2022


What does onto- mean?

Onto- is a combining form used like a prefix meaning “being.” It is occasionally used in technical terms, especially in philosophy.

The form onto- comes from Greek ṓn, meaning “being.” The Latin equivalents are ēns, ent- and essent- “being,” which are the sources of entity and essence.

What are variants of onto-?

When combined with words or word elements that begin with a vowel, onto- becomes ont-, as in ontic. When used as a suffix at the end of a word, onto- becomes -ont, as in diplont. Want to know more? Read our Words That Use articles for ont- and -ont.

Examples of onto-

One example of a term from philosophy that features the form onto- is ontology, the branch of metaphysics that studies the nature of existence. Ontology comes from the New Latin ontologia, which uses the equivalent form of onto- in the language.

The onto- part of the word means “being,” but what about the -logy part of the word? It may look familiar from words like biology; the form -logy is used to name areas of study or branches of science, from Greek logía. Ontology literally means “the study of being.”

What are some words that use the combining form onto-?

What are some other forms that onto- may be commonly confused with?

Break it down!

The combining form -geny means “origin.” With this in mind, what does the biological term ontogeny mean?

How to use onto in a sentence

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

usage for onto

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

Other Idioms and Phrases with onto

on to

see be on to.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.