# onto

Pronunciation: US say "AWN-too" /ˈɔn.tu/; UK say "ON-too" /ˈɒn.tuː/

## Preposition

1. Moving to and arriving on the surface or top of something, whether in a physical or a figurative sense.
   - Simple: Moving to a position on top of or on the surface of something.
   - _He climbed onto the roof to fix the loose antenna._
   - _The conversation drifted onto more difficult subjects after dinner._
2. Facing a place, or leading directly into it, said of doors, windows, and rooms.
   - Simple: Used to say what place a door, window, or room faces or leads straight to.
   - _Tall glass doors open onto a stone terrace above the lake._
   - _The bedroom windows face onto a quiet side street lined with maples._
3. Aware of someone's actions or intentions, especially something they hoped to keep hidden. *(colloquial)*
   - Simple: Aware of what someone is secretly doing or planning.
   - _The reporters were onto the scandal long before it broke publicly._
   - _I'm pretty sure the manager is onto our plan to leave early._
4. Used in "be onto something" to mean having hit on an idea or insight that could lead to success.
   - Simple: Used in "be onto something": to have found a good idea that could lead to success.
   - _Early sales suggest the two founders are really onto something with their app._
   - _When the third trial gave the same result, the researchers realized they were onto something._

## Other meanings

- (adjective) Describing a function that attains every value in its codomain, so that its image equals the entire codomain.
- (preposition) Introducing the codomain of a surjective function, indicating that the function attains every value in the named set.

## Origin

Formed from "on" plus "to", modeled after "into". It has been compared with Saterland Frisian "antou" ("up to").

Source: DictionaryAI, https://dictionaryai.com/define/onto (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).