'Clean' in the Bible

From all the clean animals you must take for yourself {seven pairs}, a male and its mate. And from the animals that [are] not clean [you must take] two, a male and its mate,

Of clean animals, and of animals which [are] not clean, and of the birds, and everything that creeps upon the ground,

And Noah built an altar to Yahweh, and he took from all the clean animals and from all the clean birds, and offered burnt offerings on the altar.