Definition of "Stumble" :

noun: an unintentional but embarrassing blunder

noun: an unsteady uneven gait

verb: make an error

verb: miss a step and fall or nearly fall

"She stumbled over the tree root."

verb: walk unsteadily

"The drunk man stumbled about."

verb: encounter by chance

"I stumbled across a long-lost cousin last night in a restaurant."