the GNU version of the Collaborative International Dictionary of English
adj. Not capable of being extended; not elastic.
The Century Dictionary and Cyclopedia
That cannot be stretched; not extensible: applied in geometry to a surface which can be bent in any way, but only so that each element remains unchanged in magnitude and shape.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not extensile
Word Usage
"Taken to the extreme, that would mean it was inextensible beyond EverQuest."