n. A communist who operated underground and was therefore not available for a political leadership position.
The Century Dictionary and Cyclopedia
Not available; not capable of being used with advantage: as, unavailable manuscripts.
Useless; vain.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not available or accessible or at hand
Word Usage
"If a publisher tells them to not discount a book, Amazon will simply declare the title unavailable, or uncertain, even when it is available and certain."