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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

Several government buildings in the capital have put up banners of the president, while officials have added his name onto the Kennedy Center for the performing arts and the dismantled US Institute of Peace.

From Barron's • Apr. 28, 2026

The Lakers finished the regular season with three consecutive wins to hold onto home-court advantage as the fourth seed.

From Los Angeles Times • Apr. 28, 2026

Galapagos tortoises are trained to step onto scales, for example, the lions and tigers to present their tails so blood tests and skin samples can be taken.

From BBC • Apr. 28, 2026

Every barrel that can’t leave the country through normal export channels must go somewhere: into a tank, onto a ship, into an improvised storage site—or remain underground.

From The Wall Street Journal • Apr. 28, 2026

My feeling of quiet relief, though, disappears when we turn onto our street.

From "Red Flags and Butterflies" by Sheryl Azzam