one-drop1
/ˈwʌndrɒp/originally Jamaican
noun
A type of drum rhythm used in reggae music, with strong emphasis on the third beat rather than the expected first and third in a bar of four beats; (also) music featuring this type of rhythm. Chiefly attributive: designating such a rhythm or type of music.
Origin
1970s. From one + drop.
one-drop2
/ˈwʌndrɒp/US. Now chiefly historical
adjective
Attributive Designating an ideology in which a person is regarded as black if he or she has even the smallest degree of black African ancestry. Frequently in one-drop rule, one-drop theory.
Origin
1920s; earliest use found in Pittsburgh Courier. From one + drop.