| optional(adjective, extra, worthless, possible, pointless) |
| unnecessary(adjective, required) |
| additional(adjective, casual, useless, extra, worthless) |
| alternative(adjective, open, free, voluntary, elective) |
| arbitrary(adjective, open, free, voluntary, elective) |
| casual(adjective, useless, extra, worthless, unwarranted) |
| chance(adjective, casual, useless, extra, worthless) |
| discretional(adjective, open, free, voluntary, elective) |
| discretionary(adjective, open, free, voluntary, elective) |
| elective(adjective, open, free, voluntary) |
| extra(adjective, open, free, unnecessary, superfluous) |
| extraneous(adjective, casual, useless, extra, worthless) |
| extrinsic(adjective, casual, useless, extra, worthless) |
| facultative(adjective, open, free, voluntary, elective) |
| no strings attached(expression, adjective, idiom, open, free) |
| nonobligatory(adjective, open, free, voluntary, elective) |
| not required(expression, adjective, idiom, open, free) |
| prodigal(adjective, casual, useless, extra, worthless) |
| uncritical(adjective, casual, useless, extra, worthless) |
| undesirable(adjective, casual, useless, extra, worthless) |