onto
- 01 A2 Elementary
prep.to a position on the surface of something.
prep.indicating movement toward a position on or atop a surface.
Simple“The cat jumped onto the kitchen table to reach the food.”
In context“The hikers climbed onto the rocky ledge to get a better view of the valley below as the fog began to clear.”
PitfallShe stepped on to the stage. She stepped onto the stage.Use 'onto' as one word when it means movement to a place. Use 'on to' as two words only if 'on' is part of a phrasal verb, like 'walk on to the next town'.
- 02 B2 Upper Intermediate
prep.knowing about someone's secret or bad behavior.
prep.indicating awareness of someone's true intentions or illicit activities.
Simple“The police are onto his plan, so he will probably be caught soon.”
In context“The manager realised the staff were onto her strategy to reduce overtime, leading to a tense meeting on Monday morning.”
Synonymsaware ofwise to - 03 C2 Proficiency
adj.a special type of math rule where every possible result is used.
adj.describing a function where every element in the codomain is the image of at least one element from the domain.
Simple“In this math problem, we need to prove that the function is onto.”
In context“The professor demonstrated that while the mapping was continuous, it was not onto, as several values in the target set remained unreached.”
UsageIn mathematics, this is often used as a predicative adjective following the verb 'to be'.
Synonymssurjective
Usage onto water
From on + to, after into. Compare Saterland Frisian antou (“up to”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.