(noun) A toddler or a young child who is not yet old enough to walk so crawls using all four limbs instead. A newborn baby or children under one-year old are sometimes referred to as rug rats.
Tom and Angela's little rug rat is only ten months old and he'll be walking on his own any day now.
Children, especially really annoying, hyper children who always seem to be getting into trouble and/or everyone's way.
Can't I ever get a good quiet meal at this restaurant? Every time I go here, there are always a few rug rats running around who don't look where they're going!
