0 past simple and past participle of stumble
1 to step awkwardly while walking or running and fall or begin to fall:
2 to make a mistake, such as repeating something or pausing for too long, while speaking or playing a piece of music:
Some years ago a farmer working his field stumbled on the entrance of a shaft tomb.
He stumbled, inarticulate and inchoate, unable to defend the abysmal record of his government.
I honestly don't remember much of what was said until we stumbled on a shared love of baseball.
It appears that social psychology is a discipline that has stumbled onto a series of interesting phenomena that, so far, elude systematic scientific inquiry.
Indeed, one sometimes feels as if one has stumbled into a private party of some mutual admiration society !
Biologists had stumbled across a new form of microbial life without recognizing that they had done so.
At least one critic stumbled on precisely this point.
I seemed to have stumbled on a way to gather data to generate plausible new ideas.