英语词源字典 - 在线词源网站

diligent (adj.)[diligent 词源字典]: mid-14c., from Old French diligent (14c.), from Latin diligentem "attentive, assiduous" (see diligence). Related: Diligently.[diligent etymology, diligent origin, 英语词源]
hunt (v.): Old English huntian "chase game," related to hentan "to seize," from Proto-Germanic *huntojan (cognates: Gothic hinþan "to seize, capture," Old High German hunda "booty"), from PIE *kend-.

General sense of "search diligently" (for anything) is first recorded c. 1200. Related: Hunted; hunting. Happy hunting-grounds "Native American afterlife paradise" is from "Last of the Mohicans" (1826).
sedulous (adj.): 1530s, from Latin sedulus "attentive, painstaking, diligent, busy, zealous," probably from sedulo (adv.) "sincerely, diligently," from sedolo "without deception or guile," from se- "without, apart" (see secret) + dolo, ablative of dolus "deception, guile," cognate with Greek dolos "ruse, snare." Related: Sedulously; sedulousness.
studious (adj.): mid-14c. (implied in studiously) "zealous, diligent, eager," from Latin studiosus "devoted to study, assiduous, zealous," from studium "eagerness, zeal" (see study). From late 14c. as "eager to learn, devoted to learning," also, as noun, "those who study or read diligently." Related: Studiousness.