Wiktionary
in the buff
a. (context idiomatic informal English) nude. adv. (context idiomatic informal English) While nude.
WordNet
in the buff
adj. (used informally) completely unclothed [syn: bare-assed, bare-ass, in the altogether, in the raw, raw, peeled, naked as a jaybird, stark naked]
Usage examples of "in the buff".
The big house was comfortable enough for walking around in the buff.
Oh, you may point out that of all my prancing-partners she was by far the smallest, and that when I saw her in the buff, even with her face veiled, I should have recollected the tiny nymph of Mississippi.
To her, they looked as if they were preparing to take a long hike through the desert in the buff-colored skinny tops and shorts, the clunky boots and long-billed caps.