Meaning

noun a person who takes part in an armed rebellion against the constituted authority (especially in the hope of improving conditions)

noun a member of an irregular armed force that fights a stronger force by sabotage and harassment

adjective in opposition to a civil authority or government

originFrom Latin īnsurgentem, accusative singular of īnsurgēns, present active participle of īnsurgō (“to rise up against, revolt”), from in (“against”) + surgō (“to rise”), itself from sub (“up from below”) + regō (“to guide, direct, rule, govern, administer”), from Proto-Indo-European *h₃reǵ- (“to move in a straight line, to rule, guide, lead straight, put right”).

Etymology from Wiktionary, CC BY-SA 3.0