Merriam-Webster's Collegiate® Dictionary, 11th Edition
STUMBLE
I. verb (stumbled; stumbling)
Etymology: Middle English, probably of Scandinavian origin; akin to Norwegian dialect stumle to stumble
Date: 14th century
intransitive verb
1. to fall into sin or waywardness, to make an error ; blunder , to come to an obstacle to belief, to trip in walking or running,
3. to walk unsteadily or clumsily, to speak or act in a hesitant or faltering manner,
4. to come unexpectedly or by chance , to fall or move carelessly, transitive verb to cause to stumble ; trip , bewilder , confound , stumbler noun stumblingly adverb
II. noun
Date: 1547
an act or instance of stumbling