On-Upon | Commonly Confused Words

Upon

/ə'pɔn/

Shows something happening because of or immediately after an event or action

All gaze upon him, and all do him honour.But yestermorn I turned my back upon it;'The sins of the fathers will be visited upon the children.'

/ɒn/

Indicating a position touching or in contact with the surface of a place or object

I think the wallet is on the table.From then on she took control of everything.He turned and put his hand on Silver Blaze is back.

This word has no antonyms

On is a preposition that refers to a position in contact with a surface or when something is supported by something else.
Upon is often used more formally than on and can imply something that happens immediately after something else.
On is commonly used in everyday speech, whereas upon is often seen in literary contexts.
Remember that upon is less commonly used in modern spoken English than on.
Consider upon as being more dramatic or poetic than on, which is practical and straightforward.