adjective.
Capable of being extended or protruded.
adjective.
Of or relating to a programming language or a system that can be modified by changing or adding features.
The Century Dictionary and Cyclopedia
Capable of being extended; admitting of being stretched in length or breadth; susceptible of enlargement or expansion.
In zoology, capable of being thrust out; extensile; protrusile.
the GNU version of the Collaborative International Dictionary of English
adjective.
Capable of being extended, whether in length or breadth; susceptible of enlargement; extensible; extendible; -- the opposite of contractible or compressible.