upon

American  

[uh-pon, uh-pawn] / əˈpɒn, əˈpɔn /

preposition

1. up and on; upward so as to get or be on.

   He climbed upon his horse and rode off.

2. in an elevated position on.

   There is a television antenna upon every house in the neighborhood.

3. in or into complete or approximate contact with, as an attacker or an important or pressing occasion.

   The enemy was upon us and our soldiers had little time to escape. The Christmas holiday will soon be upon us and we have hardly begun to buy gifts. The time to take action is upon us.

4. immediately or very soon after.

   She went into mourning upon her husband's death.

5. on the occasion of.

   She was joyful upon seeing her child take his first steps.

6. on (in any of various senses, used as an equivalent of on with no added idea of ascent or elevation, and preferred in certain cases only for euphonic or metrical reasons).

   He swore upon his honor as a gentleman.

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upon British  

/ əˈpɒn /

preposition

1. another word for on

2. indicating a position reached by going up

   climb upon my knee

3. imminent for

   the weekend was upon us again

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upon Idioms  

1. see act on (upon); call on (upon); chance on (upon); come across (upon); come on (upon); count on (upon); dawn on (upon); dwell on (upon); enter on (upon); fall back on (upon); fall on (upon); grow on (upon); hard on (upon); hit on (upon); incumbent upon; light on (upon); once upon a time; pitch on (upon); play on (upon); put upon; seize on (upon); set at (upon); take it upon oneself; wait on (upon); weigh on (upon); work on (upon).

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Etymology

Origin of upon

First recorded in 1150–1200; Middle English; up (adverb) + on (preposition)

Example Sentences

Depending on how that is interpreted and acted upon, however, could violate international agreements on space exploration.

From Salon • Apr. 9, 2026

Physicist Alain Aspect was awarded a Nobel Prize in 2022 for his experiments with entangled photons, the framework Pasqal was built upon.

From Barron's • Apr. 8, 2026

The court heard Roberts spent 22 "exemplary" years in the Army serving in Yugoslavia, Northern Ireland, Iraq and Afghanistan, then upon his release immediately joined Durham Police before moving to Northumbria in 2017.

From BBC • Apr. 7, 2026

“He testified Ms. Brooks would pick the ‘KP’ or kitchen patrol person based upon that person’s fighting prowess,” the motion said.

From Los Angeles Times • Apr. 7, 2026

Magic shouted with glee, not caring in the least what the trick was or upon whom it was to be played.

From "The Very, Very Far North" by Dan Bar-el