General:
* Brown
* Tawny
* Chestnut
* Hazel
* Sienna
* umber
Light Brown:
* Tan
* Beige
* Caramel
* Sandy
* Cream
* Fawn
Dark Brown:
* Mocha
* Espresso
* Mahogany
* Walnut
* Chocolate
* Sepia
Earthy/Natural:
* Russet
* Clay
* Mud
* Bark
* Earth
* Moss
Warm/Rich:
* Bronze
* Copper
* Auburn
* Rust
* Caramel
* Mahogany
Cool/Dull:
* Greyish-brown
* Dusty brown
* Muddy brown
* Ashy brown
Descriptive:
* Deep
* Rich
* Warm
* Cool
* Dull
* Vivid
* Bright
* Dark
* Light
* Pale
Figurative:
* Earth-toned
* Woodsy
* Rustic
* Autumnal
* Coffee-colored
Other:
* Brunette
* Bay (horse color)
* Liver (color of a liver)
* Prune (color of a prune)
* umber
* umber
Note: The best word to use will depend on the specific shade of brown and the context in which it is being used.