adjective
given or done without compulsion, need, or warrant
people who offer supererogatory advice
Synonyms: gratuitous, supererogant, supererogative, unasked, uncalled-for, wanton
Related Word: nonessential, superfluous, supernumerary, unnecessary, unneeded
Contrasted words: essential, indispensible, vital; compulsory, obligatory; called-for, needful, required, requisite, sought, wanted