ˈblak.ˌwu̇d- noun
Usage: usually capitalized B
Etymology: after Easley F. Blackwood, 20th century American who devised it
: a bidding method used in reaching slam contracts in contract bridge and consisting of the use of four no-trump as an asking bid to which the bidder's partner is supposed to respond five clubs if he holds no ace, five diamonds if he holds one ace, five hearts if he holds two aces, five spades if he holds three aces, or five no-trump if he holds four aces and the use of five no-trump as an asking bid to which the bidder's partner is supposed to respond six clubs with no king, six diamonds with one king, six hearts with two, six spades with three, or six no-trump with four