A natural is a term in several gambling games; in each case it refers to one or two specific good outcomes, usually for the player, often involves achieving a particular score in the shortest and fastest manner possible.
At blackjack, the best possible hand for the player is to reach a score of 21 with exactly two cards, which necessarily involves an ace and a ten-valued card (such as a 10, a Jack, a Queen or a King). This hand, which usually defeats any other hand of 21 and carries a higher pay-out of winnings, is referred to as a "blackjack" or a "natural"[1].
At craps, a natural is a roll of two dice with a score of 7 or 11 with on the first roll of a shooter's game. This will lead to winnings for the players who wagered money on the "pass line" bet.
At punto banco, a natural is a two-card hand totaling 8 or 9, for either the player or the banker.