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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-

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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

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Example Sentences

See Examples For:

onto

A nuclear explosion could potentially protect Earth from an incoming asteroid by releasing powerful X-rays that heat its surface and push it onto a safer trajectory.

From Science Daily ● Nov. 8, 2026

Pulse oximeters, clipped onto fingers in every hospital, were cleared under 2013 Food and Drug Administration guidance that asked for as few as two darkly pigmented test subjects.

From The Wall Street Journal ● Nov. 6, 2026

Meieran has been outspoken about the challenges of running a large nightlife business downtown but held onto the brand, he says, because Clifton’s is a rarity, a unique only-in-California business.

From Los Angeles Times ● Nov. 6, 2026

But Ronaldo's two late headers in a World Cup qualifying win over the Republic of Ireland in 2021 took him onto 111 goals.

From BBC ● Nov. 5, 2026

“I don’t think sending scores of people out onto a lake in paper boats screams of brilliance,” Zara says.

From "Red Flags and Butterflies" by Sheryl Azzam

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