stumble across/on/onto/upon

:  to fall into sin or waywardness

:  to make an error :  blunder

:  to come to an obstacle to belief

:  an act or instance of stumbling

:  from one side to the opposite side of :  over, through

:  on the opposite side of

:  so as to intersect or pass through at an angle

:  in a position reaching from one side to the other :  crosswise

:  to or on the opposite side

:  so as to be understandable, acceptable, or successful

:  being in a crossed position

:  to a position on

:  in or into a state of awareness about

: used as a function word to indicate a set each element of which is the image of at least one element of another set

:  mapping elements in such a way that every element in one set is the image of at least one element in another set

:  on

:  on the surface :  on it

:  thereafter, thereon