ɪn ɪts ɚɹˈɪdʒɪnəl fˈɔːɹm, blˈækwʊd ɪz ɐn ˌɑːɹɾɪfˈɪʃəl fˈoːɹ nˈɑːtɹʌmp bˈɪd fˈoːɹ ˌɛntˈiː wˌɪtʃ ˈæsks pˈɑːɹtnɚ tə dɪsklˈoʊz ðə nˈʌmbɚɹ ʌv ˈeɪsᵻz ɪn hɪz hˈænd.
In its original form, Blackwood is an artificial four notrump bid (4NT) which asks partner to disclose the number of aces in his hand.