Mahogany was a type of wood.
It was often used in the manufacture of desks. Hade, (TV: The Sun Makers) Adolf Hitler, (PROSE: Timewyrm: Exodus) Huldah (PROSE: Timewyrm: Apocalypse) and Peter Wise (PROSE: Who Killed Kennedy) all had mahogany desks.
Hade pronounced the name "mah-hog-gay-knee". (TV: The Sun Makers)
The Doctor had a mahogany hatstand in the TARDIS. (PROSE: The Underwater Menace, Timewyrm: Apocalypse, The Highest Science)