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• onto
  onto

  preposition

  to a place or position on; upon; on.
• onto-
  onto-

  a combining form meaning “being,” used in the formation of compound words.

onto

¹ American  

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

preposition

1. to a place or position on; upon; on.

   to get onto a horse.

2. Informal. in or into a state of awareness about.

   I'm onto your scheme.

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adjective

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

onto- ² American  

1. a combining form meaning “being,” used in the formation of compound words.

   ontogeny.

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onto ¹ British  

/ ˈɒntə, ˈɒntʊ /

preposition

1. to a position that is on

   step onto the train as it passes

2. having become aware of (something illicit or secret)

   the police are onto us

3. into contact with

   get onto the factory

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onto- ² British  

combining form

1. existence or being

   ontogeny

   ontology

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Usage

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.

Etymology

Origin of onto¹

First recorded in 1575–85; on + to

Origin of onto-²

< New Latin < Greek ont- (stem of ón, neuter present participle of eînai to be) + -o- -o-

Compare meaning

How does onto compare to similar and commonly confused words? Explore the most common comparisons:

• onto vs. one-to-one
• unto vs. onto

Example Sentences

See Examples For:

onto

Bulgaria, Romania and Turkey all front onto the Black Sea, an arena of drone combat by both Ukraine and Russia.

From Barron's ● Aug. 8, 2026

The concentrated sunlight can then be directed onto the tiny nonlinear crystal responsible for producing the entangled photons.

From Science Daily ● Aug. 8, 2026

More than a hundred influencers have already signed onto the program, which is rolling out in November, Lore said.

From The Wall Street Journal ● Aug. 7, 2026

Fhimah placed it onto a conveyor belt, introducing the unaccompanied bag into the international baggage system, tagged to be flown to the US.

From BBC ● Aug. 7, 2026

Renn knelt by the fire and tipped her load onto the ground.

From "Wolf Brother" by Michelle Paver