c. 1500, from French inélégant (15c.), from Latin inelegantem (nominative inelegans) "not elegant, not choice," also "without taste, without judgment," from in- "not" (see in- (1)) + elegans (see elegant). Related: Inelegantly.
word-forming element meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant, a tendency which began in later Latin), from Latin in- "not," cognate with Greek an-, Old English un-, all from PIE root *ne- "not."
In Old French and Middle English often en-, but most of these forms have not survived in Modern English, and the few that do (enemy, for instance) no longer are felt as negative. The rule of thumb in English has been to use in- with obviously Latin elements, un- with native or nativized ones.
late 15c., "tastefully ornate," from Old French élégant (15c.) and directly from Latin elegantem (nominative elegans) "choice, fine, tasteful," collateral form of present participle of eligere "select with care, choose" (see election). Meaning "characterized by refined grace" is from 1520s. Latin elegans originally was a term of reproach, "dainty, fastidious;" the notion of "tastefully refined" emerged in classical Latin. Related: Elegantly.
Elegant implies that anything of an artificial character to which it is applied is the result of training and cultivation through the study of models or ideals of grace; graceful implies less of consciousness, and suggests often a natural gift. A rustic, uneducated girl may be naturally graceful, but not elegant. [Century Dictionary]
<a href="https://www.etymonline.com/word/inelegant">Etymology of inelegant by etymonline</a>
Harper, D. (n.d.). Etymology of inelegant. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/inelegant