unmotivated (adj.)youdaoicibaDictYouDict[unmotivated 词源字典]
"lacking in motivation," by 1917, from un- (1) "not" + past participle of motivate. Meaning "lacking in motive" is attested from 1871. Unmotived is from 1794.[unmotivated etymology, unmotivated origin, 英语词源]