Definition of base on/upon
: to form, make, or develop (something, such as an opinion, decision, or calculation) by using (something, such as information) as a basis, starting point, etc. You've based your opinion on faulty information. The story is based on real-life events. The island's economy is based on tourism.
Word by Word Definitions
: the lower part of a wall, pier, or column considered as a separate architectural feature
: the lower part of a complete architectural design (as of a monument)
: the bottom of something considered as its support : foundation
: of little height
: low in place or position
: on the surface : on it
: thereafter, thereon
Seen and Heard
What made you want to look up base on/upon? Please tell us where you read or heard it (including the quote, if possible).