noun. 1. a. Any of various tropical American evergreen trees of the genus Swietenia, valued for their hard, reddish-brown wood. b. The wood of any of these trees, especially that of S. mahogani, used in making furniture. 2. a. Any of several trees having wood resembling true mahogany. b. The wood of any of these trees. 3. Color. A moderate reddish brown, mahogani.