tumble over
to fall over. The vase tumbled over and broke. I held Timmy up to keep him from tumbling over.
tumble over someone or something
to trip or stumble over someone or something and fall down. I tumbled over Fred, who was napping under the tree. I tumbled over a chair and fell down.
tumble over (something)
to fall over the edge of something. Stay away from the edge. I don't want any of you tumbling over it. Don't go too close. You'll tumble over.