1. build upon - be based on; of theories and claims, for example; "What's this new evidence based on?" build on, repose on, rest on. depend on, depend upon, devolve on, hinge on, hinge upon, turn on, ride - be contingent on; "The outcomes rides on the results of the election"; "Your grade will depends on your homework"

Is it building on or building upon?

1 Answer. "Upon" is more formal than "on".

How do you say building upon?