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

The fossils also showed that early snakes held onto their hindlimbs for a long time before the rise of the mostly limbless snakes alive today.

From Science Daily • Apr. 24, 2026

Hangzhou-based DeepSeek burst onto the scene in January last year with a generative AI chatbot, powered by its R1 reasoning model, that upended assumptions of US dominance in the strategic sector.

From Barron's • Apr. 24, 2026

Adding unpaid labor onto one’s daily workload is draining and, provided your domestic partner is open to ameliorating the imbalance, solvable.

From Salon • Apr. 23, 2026

Martel said those higher costs have largely been passed onto customers.

From The Wall Street Journal • Apr. 22, 2026

He tipped some red ochre onto his palm, and spat on it.

From "Wolf Brother" by Michelle Paver