onto

1. 1
   to a surfacepreposition

   Moving to and arriving on the surface or top of something, whether in a physical or a figurative sense.

   He climbed onto the roof to fix the loose antenna.

   The conversation drifted onto more difficult subjects after dinner.

   UsageWrite onto for movement to a surface, but on to when on belongs to the verb: drove on to the coast.

   Similaron, upon

   Oppositeoff

   Note

   A preposition built from on and to on the pattern of into, and it works the same way: it marks movement that ends on a surface, whether a cat landing on a keyboard or a drug arriving on the market.

2. 2
   doors facingpreposition

   Facing a place, or leading directly into it, said of doors, windows, and rooms.

   Tall glass doors open onto a stone terrace above the lake.

   The bedroom windows face onto a quiet side street lined with maples.

   UsageAfter open, look, face or give: a door opens onto the garden.

3. 3
   aware ofprepositioncolloquial

   Aware of someone's actions or intentions, especially something they hoped to keep hidden.

   The reporters were onto the scandal long before it broke publicly.

   I'm pretty sure the manager is onto our plan to leave early.

   UsageUsually be onto someone or something: the police are onto us.

4. 4
   preposition

   Used in "be onto something" to mean having hit on an idea or insight 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.

   Note

   A fixed frame with an open object: the something stays vague because the payoff has not come yet. Speakers often hedge or boost it (you might be onto something, they were really onto something). Keep it apart from the "aware of" meaning: being onto someone means having seen through their scheme, while being onto something means being on the track of a discovery or a success.

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