When we stumble on something, we unexpectedly come across it. There are many different synonyms for this phrase that can be used to convey the same meaning in different ways. For example, we might say that we accidentally stumbled upon something, that we unexpectedly encountered it, or that we unexpectedly found it. Other synonyms could include discovering something unexpectedly, happening upon something, or coming across something by chance. No matter which word you choose, the meaning remains the same - stumbling on something speaks to the element of surprise and unexpectedness that comes with discovering something new.