an unsteady uneven gait
an unintentional but embarrassing blunder; "he recited the whole poem without a single trip"; "he arranged his robes to avoid a trip-up later"; "confusion caused his unfortunate misstep"
walk unsteadily; "The drunk man stumbled about"
miss a step and fall or nearly fall; "She stumbled over the tree root"
encounter by chance; "I stumbled across a long-lost cousin last night in a restaurant"
make an error; "She slipped up and revealed the name"