The Collaborative International Dictionary of English v.0.48:

Industrious \In*dus"tri*ous\, a. [L. industrius, industriosus:
   cf. F. industrieux. See Industry.]
   [1913 Webster]
   1. Given to industry; characterized by diligence; constantly,
      regularly, or habitually occupied; busy; assiduous; not
      slothful or idle; -- commonly implying devotion to lawful
      and useful labor.
      [1913 Webster]

            Frugal and industrious men are commonly friendly to
            the established government.           --Sir W.
                                                  Temple.
      [1913 Webster]

   2. Steadily and perseveringly active in a particular pursuit
      or aim; as, he was negligent in business, but industrious
      in pleasure; an industrious mischief maker.
      [1913 Webster]

            Industrious to seek out the truth of all things.
                                                  --Spenser.
      -- In*dus"tri*ous*ly, adv. -- In*dus"tri*ous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

industrious
    adj 1: characterized by hard work and perseverance [syn:
           hardworking, industrious, tireless, untiring]
    2: working hard to promote an enterprise [syn: energetic,
       gumptious, industrious, up-and-coming]