buff

Concise Oxford English Dictionary © 2008 Oxford University Press:
buff1

▶noun

• 1 a yellowish-beige colour.

• 2 a dull yellow leather with a velvety surface.

• 3 a cloth or pad used for polishing.

▶verb polish (something).

■ give (leather) a velvety finish by removing the surface of the grain.

▶adjective (also buffed) N. Amer. informal in good physical shape; muscular.

– phrases
in the buff informal naked.

– origin C16: prob. from Fr. buffle, from Ital. bufalo, from late L. bufalus (see buffalo).

Concise Oxford English Dictionary © 2008 Oxford University Press:
buff2

▶noun informal a person who is interested in and very knowledgeable about a particular subject: a computer buff.

– origin early 20th cent.: from buff1, orig. applied to fire-watchers, because of the buff uniforms worn by New York firemen.