1560s, "triumph over in an arrogant way" (obsolete), from French insulter "to wrong; reproach; triumph arrogantly over," earlier "to leap upon" (14c.) and directly from Latin insultare "to assail, to make a sudden leap upon," which was used by the time of Cicero in sense of "to insult, scoff at, revile," frequentative of insilire "leap at or upon," from in- "on, at" (from PIE root *en "in") + salire "to leap" (see salient (adj.)).
Sense of "verbally abuse, affront, assail with disrespect, offer an indignity to" is from 1610s. Related: Insulted; insulting.
c. 1600, "an attack;" 1670s as "an act of insulting, contemptuous treatment," from French insult (14c.) or directly from Late Latin insultus "insult, scoffing," noun use of past participle of insilire, literally "to leap at or upon" (see insult (v.)). The older noun was insultation (1510s). To add insult to injury translates Latin injuriae contumeliam addere.