Synonyms for Discretionary (same or very similar meaning)
WordNet sense 1 (not subject to or subjected to restriction):
unrestrictedWordNet sense 2 (having or using the ability to act or decide according to your own discretion or judgment):
discretionalWordNet sense 3 (based on or subject to individual discretion or preference or sometimes impulse or caprice):
arbitraryFrom the ODE community, based on WordNetadd/edit