Rohan: Substituting the dictionary meanings of 'de' (of, from, by, since) gives weird stuff in English...

Butler's dictionary classifies the meanings of de into three groups, related to 'of', 'from' and 'by'. 'On' is under the 'from' heading (section 2f). Etymologically the sense is that of 'hanging from'. CEED translates 'depend on' as dependi de. Well's dictionary (and the lernu dictionary) don't have the 'on' rendering, however.

lernu's dictionary is not really meant to be a substitute for a good paper dictionary (though of course we are constantly trying to improve it). I would personally be very hesitant to include "on" as a possible meaning for "de" in the dictionary, at least without extensive context information. De tends to translate as "on" only in very idiomatic contexts.