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