n (context|medicine|slang) An unlikelydiagnosis, especially for symptoms probably caused by a common ailment. (Originates in the advice often given to medical students: "When you hear hoof beats, think of horses, not zebras.")
n (context|vulgar|pejorative|slang) A bi-racial person, specifically one born to a member of the Sub-Saharan African race and a Caucasian.