DILIGENT Copy link • DILIGENTdiligens: industrius: sedulus: assiduus [SYN. in ASSIDUOUS]: gnavus or navus: impiger. To be diligent in business, in re gerenda acrem et industrium esse: diligent in anything, diligens alicujus rei or in re (accurate, careful, and prudent in anything; opposed to negligens).