WordNet sense 1 (encounter by chance):

hit

WordNet sense 2 (walk unsteadily):

bumble, falter

WordNet sense 3 (miss a step and fall or nearly fall):

trip

WordNet sense 4 (make an error):

trip up

WordNet sense 5 (an unsteady uneven gait):

lurch, stagger

WordNet sense 6 (an unintentional but embarrassing blunder):

misstep, trip-up