Dictionary.com
Thesaurus.com
Synonyms

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.


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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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).


Etymology

Origin of upon

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Upon winning the Emmy Award for actress in a comedy, O'Hara thanked her co-stars Eugene and Dan Levy for giving her the opportunity to play "a woman of a certain age - my age - who gets to fully be her ridiculous self".

From BBC

Upon entering, however, you discover that the house is really a sequence of staged sensations in which detail has been fine-tuned for maximal theatrical effect.

From The Wall Street Journal

Those who followed drew upon their example to enrich and expand the canon during the subsequent decades.

From The Wall Street Journal

When funding stalemates occur in other countries, government activity generally continues with the existing levels of funding until new monies can be agreed upon.

From The Wall Street Journal

It cuffed them all into silence, and they watched the griffin pounce upon the butterfly and miss.

From Literature