The term 'stumble on' can be defined as to find something by CHANCE or happenstance. The crossword solutions for this term are UNCOVER (7 letters), DISCOVER (8 letters), CHANCE (6 letters), and HAPPEN (6 letters). These words all have the same meaning, which is to find something unexpectedly or without looking for it. UNCOVER and DISCOVER both imply that something was hidden and then found, while CHANCE and HAPPEN suggest that the finding was accidental or unexpected.