optional

• POS: Adjective
• HYPHEN: op=tion=al

CIDE DICTIONARY

optional, a. 

 Involving an option; depending on the exercise of an option; left to one's discretion or choice; allowed but not compulsory; as, optional studies; it is optional with you to go or stay.  [1913 Webster]
"If to the former the movement was not optional, it was the same that the latter chose when it was optional."  [1913 Webster]
"Original writs are either optional or peremptory."  [1913 Webster]

OXFORD DICTIONARY

optional, adj. being an option only; not obligatory.

Derivative

optionality n. optionally adv.

THESAURUS

optional

alternative, arbitrary, autonomous, discretional, discretionary, disjunctive, elective, free, free will, gratuitous, independent, nonmandatory, offered, proffered, self-acting, self-active, self-determined, self-determining, spontaneous, unasked, unbesought, unbidden, uncalled-for, uncoerced, uncompelled, unforced, uninfluenced, uninvited, unpressured, unprompted, unrequested, unrequired, unsolicited, unsought, volitional, voluntary, volunteer, willful

ROGET THESAURUS

optional

Will

N will, volition, conation, velleity, liberum arbitrium, will and pleasure, free will, freedom, discretion, option, voluntariness, spontaneity, spontaneousness, originality, pleasure, wish, mind, desire, frame of mind, intention, predetermination, selfcontrol, determination, force of will, voluntary, volitional, willful, free, optional, discretional, discretionary, volitient, volitive, minded, prepense, intended, autocratic, unbidden &c (bid), spontaneous, original, unconstrained, voluntarily, at will, at pleasure, a volonte, a discretion, al piacere, ad libitum, ad arbitrium, as one thinks proper, as it seems good to, a beneplacito, of one's won accord, of one's own free will, proprio motu, suo motu, ex meromotu, out of one's won head, by choice, purposely, deliberately, stet pro ratione voluntas, sic volo sic jubeo, a vostro beneplacito, beneficium accipere libertatem est vendere, Deus vult, was man nicht kann meiden muss man willig leiden.

Choice

N choice, option, discretion, preoption, alternative, dilemma, embarras de choix, adoption, cooptation, novation, decision, election, political election (politics), selection, excerption, gleaning, eclecticism, excerpta, gleanings, cuttings, scissors and paste, pick, preference, prelation, opinion poll, survey, predilection, optional, discretional, eclectic, choosing, preferential, chosen, choice, optionally, at pleasure, either the one or the other, or at the option of, whether or not, once and for all, for one's money, by choice, by preference, in preference, rather, before.