up‧on S2 W1 / əpɒn $ əpɑn / 介词 formal

1 used to mean ‘on’ or ‘onto’ :

an honour bestowed upon the association

We are completely dependent upon your help.

Brandon threw him upon the ground.

2 if a time or event is upon you, it is about to happen :

Winter is almost upon us.

3 layer upon layer/mile upon mile etc used to emphasize that there are a lot of layers, miles etc :

mile upon mile of golden sand

→ once upon a time at once 1 ( 14 ) , → take it upon yourself to do something at take 1 ( 27 )