A Deck out (Japanese: デッキアウト Dekki Auto) is a loss due to having no cards in the Main Deck when that player would draw a card. Mill Decks, such as "Laval", use this as their primary victory condition.
In the anime
In the anime, a Deck out has occurred only three times: Seto Kaiba decked out against Maximillion Pegasus (though in this case was more because Seto ran out of playable monster cards instead of being unable to draw a card), Strings against Yami Yugi, and Howard X Miller against Jaden Yuki. Though Kaiba's deck may have either been sent to the graveyard or banished by Crush Card Virus's effect, therefore technically being unable to draw.
Duelists such as Seto Kaiba, Ishizu Ishtar, Anubis, Zigfried von Schroeder (through Leon von Schroeder), Yami Bakura, Howard X Miller, Sartorius, Mr. Armstrong, Shadow Drone Trudge, Breo, Jean, Vector and Eliphas have attempted to cause their opponents to deck out, albeit unsuccessfully (though in Ishizu and Jean's cases, they abandoned their strategies to focus on different ones).