Pronunciation: (un"ik-spen'du-bul), [key]
1. essential; absolutely required: unexpendable resources vital to our security.
2. not capable of being expended; inexhaustible: an unexpendable source of energy.
3. not available for expenditure: The principal of the trust fund is unexpendable.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.