Synonyms of optional

1 Syllable
free
2 Syllables
icer, gravier, open, tipper, fusser, extra
3 Syllables
unneeded, free-willed, unforced, gingerbread, judgmental
4 Syllables
uncompelled, unrequired, inessential, unprescribed, unessential, volitional, uncalled-for, unrestricted, voluntary, arbitrary, elective, discretional
5 Syllables
unnecessary, nonmandatory, alternative, facultative, noncompulsory, discretionary
6 Syllables
nonobligatory