Gratuitous1. (a.) Given without an equivalent or recompense; not called for; as, gratuitous violence in a movie; conferred without valuable consideration; granted without pay, or without claim or merit; not required by justice.
2. (a.) Not called for by the circumstances; without reason, cause, or proof; adopted or asserted without any good ground; as, a gratuitous assumption.
Thesaurus Entries
God-given, accorded, aimless, allowed, amorphous, arbitrary, autonomous, baseless, bestowed, biggety, bluff, bottomless, brash, capricious, casual, charitable, cheeky, chutzpadik, cocky, complimentary, contemptuous, costless, crusty, de trop, derisive, desultory, disarticulated, discontinuous, discretional, discretionary, disjunct, disordered, dispensable, dispersed, disproportionate, disrespectful, elective, eleemosynary, erratic, excess, expendable, expenseless, expletive, facy, fitful, flip, flippant, for free, for love, for nothing, formless, free, free as air, free for nothing, free gratis, free of charge, free of cost, free will, freebie, fresh, frivolous, gally, giftlike, given, granted, gratis, groundless, haphazard, hit-or-miss, immethodical, impertinent, impudent, in excess, inchoate, incoherent, indefensible, independent, indiscriminate, irrational, irregular, malapert, meaningless, misshapen, needless, nervy, nonessential, nonmandatory, nonsymmetrical, nonsystematic, nonuniform, offered, on the house, optional, orderless, pert, planless, pleonastic, proffered, prolix, promiscuous, providential, random, reasonless, redundant, rude, sassy, saucy, self-acting, self-active, self-determined, self-determining, senseless, shapeless, smart, smart-alecky, smart-ass, spare, spasmodic, spontaneous, sporadic, straggling, straggly, supererogatory, superfluous, systemless, tautologic, tautologous, to spare, unarranged, unasked, unbesought, unbidden, unbought, uncalled-for, unclassified, uncoerced, uncompelled, undirected, unessential, unforced, unfounded, ungraded, ungrounded, uninfluenced, uninvited, unjoined, unjustifiable, unjustified, unlooked-for, unmethodical, unnecessary, unneeded, unordered, unorganized, unpaid-for, unpressured, unprompted, unrequested, unrequired, unsolicited, unsorted, unsought, unsupportable, unsymmetrical, unsystematic, untaxed, ununiform, unwarranted, unwelcome, vague, verbose, voluntary, volunteer, vouchsafed, wandering, wanton, willful, willing, wise-ass, without charge