| voluntary(adjective, feature, characteristic, open, free) |
| unforced(adjective, feature, characteristic, open, free) |
| optional(adjective, free, deliberate, natural, willing) |
| intended(adjective, feature, characteristic, free, regard) |
| intentional(adjective, feature, characteristic, free, regard) |
| spontaneous(adjective, feature, characteristic, free, regard) |
| willed(adjective, feature, characteristic, free, regard) |
| willful(adjective, free, deliberate, determined, natural) |
| willing(adjective, free, deliberate, determined, willing) |
| deliberate(adjective, feature, characteristic, free, determined) |
| free(adjective, feature, characteristic, open, deliberate) |
| unasked(adjective, feature, characteristic, free, regard) |
| unconstrained(adjective, feature, characteristic, free, regard) |
| volunteer(adjective, feature, characteristic, free, regard) |
| discretional(adjective, feature, characteristic, open, free) |
| autonomous(adjective, feature, characteristic, free, deliberate) |
| chosen(adjective, feature, characteristic, free, deliberate) |
| designful(adjective, feature, characteristic, free, deliberate) |
| discretionary(open, free, will, voluntary, elective) |
| elected(adjective, feature, characteristic, free, deliberate) |