1
general::
Phrase(s): border (up)on something
1. Lit. [for something] to touch upon a boundary. (Upon is more formal and less commonly used than on.) • Our property borders on the lakeshore. • The farm borders upon the railroad tracks. 2. Fig. [for some activity or idea] to be very similar to something else. (Not usually physical objects. Upon is formal and less commonly used than on.) • This notion of yours borders upon mutiny! • That plan borders on insanity.
McGrawhill's American Idioms And Phrasal Verbs