Nude. Naked. Unclothed. In the buff. Au naturale.
This means you aren't wearing any armor, and is usually considered a bad idea1)2)3) 4) unless you want to die.

1)
Unless you're a kittymorph, in which case it's a great idea!
2)
Also it's encouraged to be naked in the Grassy Meadow.
3)
But not if you're ugly, like Hermein.
4)
Hermein may be ugly, but he's tougher than Marv from Sin City.