Permissibility :: Permissibility (n.) The quality of being permissible; permissibleness; allowableness.
Permissible :: Permissible (a.) That may be permitted; allowable; admissible.
Permission :: Permission (n.) The act of permitting or allowing; formal consent; authorization; leave; license or liberty granted.
Permissive :: Permissive (a.) Permitting; granting leave or liberty.