1. preposition /əˈpɒn/
a) Being above and in contact with another.
Place the book upon the table.
b) Being directly supported by another.
The crew set sail upon the sea.
2. adverb /əˈpɒn/
a) Being the target of an action.
He was set upon by the agitated dogs
b) Incidental to a specified point in time or order of action; usually combined with here-, there- or where-.
The clock struck noon, whereupon the students proceeded to lunch.
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