solicit: [15] The ultimate source of solicit is Latin sollicitus ‘agitated’, which also gave English solicitous [16]. It was a compound adjective, formed from sollus ‘whole’ (source also of English solemn) and citus, the past participle of ciēre ‘move’ (source of English cite, excite, etc) – hence literally ‘completely moved’.
From it was formed the verb sollicitāre ‘disturb, agitate’, which passed into English via Old French solliciter. By the time it arrived it had acquired the additional meaning ‘manage affairs’, which lies behind the derived solicitor [15]; and the original ‘disturb’ (which has since died out) gave rise in the 16th century to ‘trouble with requests’. French insouciant, borrowed by English in the 19th century, goes back ultimately to Latin sollicitāre. => cite, excite, incite, insouciant, solemn, solid
solicit (v.)
early 15c., "to disturb, trouble," from Middle French soliciter (14c.), from Latin sollicitare "to disturb, rouse, trouble, harass; stimulate, provoke," from sollicitus "agitated," from sollus "whole, entire" + citus "aroused," past participle of ciere "shake, excite, set in motion" (see cite). Related: Solicited; soliciting.
Meaning "entreat, petition" is from 1520s. Meaning "to further (business affairs)" evolved mid-15c. from Middle French sense of "manage affairs." The sexual sense (often in reference to prostitutes) is attested from 1710, probably from a merger of the business sense and an earlier sense of "to court or beg the favor of" (a woman), attested from 1590s.