Belly, slave (noun); navel of a slave girl. Only slaves on Gor display their navels
The Forkbeard had had his girls drop their kirtles low upon their hips, and hitch them high, that their beauty might be well exhibited, from their collars to some inches below their navels, and, too, that the turns of their calves and ankles might be similarly displayed; I would have thought that they might have groaned with humiliation and attempted to hide themselves among us, but, instead, even Pudding and Thyri, they walked as proud, shameless bond-maid; the exposure of the female's navel, on Gor, is known as the "slave belly"; only female slaves expose their navels....
Book 9, Marauders of Gor: Page 143
"Do you understand the significance of the revealing of the navel?" she asked me.
"I believe on Gor," I said, "it is called 'the slave belly'."
"It is," she said. "But Gor, of course, does not exist."
"Of course not," I said.
"Now take the goblet," he said, "and hold the metal against your body, pushing inward." I took the goblet and held it, tightly, to my body. I held the round, heavy metal against me, below my brassiere. "Lower," he said, "against your belly."
I then held the goblet lower.
"Press it more inward," he said.
I did so. I can still feel the cold metal against me, firmly, partly against the silk of my undergarment, partly against my belly.
"Now," said he, "lift the goblet to your lips and kiss it lingeringly, then proffer it to me, arms extended, head down."
Book 15, Fighting Slave of Gor: Page 10