a stolen base; an instance in which a base runner advances safely during the delivery of a pitch (without the help of a hit or walk or passed ball or wild pitch)
steal a base
move stealthily; "The ship slipped away in the darkness"
take without the owner's consent; "Someone stole my wallet on the train"; "This author stole entire paragraphs from my dissertation"
(figurative) a course of action that is unproductive and offers no hope of improvement; "all the clues led the police into blind alleys"; "so far every road that we've been down has turned out to be a blind alley"