"constant in effort to accomplish what is undertaken," mid-14c., from Old French diligent (14c.) and directly from Latin diligentem (nominative diligens) "attentive, assiduous, careful," present-participle adjective from diligere "single out, value highly, esteem, prize, love; aspire to, be content with, appreciate," originally "to pick out, select," from dis- "apart" (see dis-) + legere "choose, gather," from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')." Related: Diligently.
