Yes, indestructible is a word. It means incapable of being destroyed.
Illegible.
unalienable
The opposite of the word capable is incapable.
my best guess is permanent
indescribableIneffable. -adjective 1. incapable of being expressed or described in words; inexpressible: ineffable joy.
He was incapable of performing even the most trivial task.
Audible."inaudible" quite literally means "incapable of being heard"; by stripping the prefix "in-", you get the word "audible", which indeed means "capable of being heard".
immobile paralyzed
No one could change or improve the girl's incorrigible behavior.
in (prefix) = not alien (root) = outside able (suffix) = adjective Definition: incapable of being alienated, surrendered, or transferred
No, "uncapable" is not a prefix. It is a word that combines the prefix "un-" meaning "not" with "capable" to form a word that means "not capable."