" electively "

1: as in optionally;

•  Synonyms : 

•  optionally,

•  alternately,

•  alternatively,

•  either,

•  instead,

•  desirably,

•  gladly,

•  wishfully,

•  fain,

•  first,

•  preferably,

•  rather,

•  readily,

•  soon,

•  willingly,

•  obligingly,

•  voluntarily

•  Antonyms : 

•  involuntarily,

•  unwillingly,

•  reluctantly,

•  forcibly,

•  willy-nilly

1: subject to one's freedom of choice;

  * e.g., " ... a plastic surgeon who mainly does face-lifting and other kinds of elective surgery "

•  Synonyms : 

•  discretionary,

•  optional,

•  voluntary

•  Antonyms : 

•  compulsory,

•  mandatory,

•  nonelective,

•  nonvoluntary,

•  obligatory,

•  required