germ-free (thing)

1. An animal (for instance, a mouse raised for experimental purposes) which has no microorganisms whatsoever living in or on it.
2. An animal which was born and raised in an isolated environment with no microorganisms in it.

1. A chamber which has absolutely no microorganisms whatsoever living in it, where a germ-free animal can be born and raised.
2. An artificial barrier surrounding a living facility for germ-free animals, which keeps out all microorganisms.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.