restrained (adj.)youdaoicibaDictYouDict[restrained 词源字典]
"repressed, kept under control," 1570s, past participle adjective from restrain.[restrained etymology, restrained origin, 英语词源]
unconstrained (adj.)youdaoicibaDictYouDict
1640s, from un- (1) "not" + past participle of constrain (v.). Related: Unconstrainedly.
unrestrained (adj.)youdaoicibaDictYouDict
1580s, from un- (1) "not" + past participle of restrain (v.). Related: Unrestrainedly.