The Collaborative International Dictionary of English v.0.48:

Languid \Lan"guid\, a. [L. languidus, fr. languere to be faint
   or languid: cf. F. languide. See Languish.]
   [1913 Webster]
   1. Drooping or flagging from exhaustion; indisposed to
      exertion; without animation; weak; weary; heavy; dull. "
      Languid, powerless limbs. " --Armstrong.
      [1913 Webster]

            Fire their languid souls with Cato's virtue.
                                                  --Addison.
      [1913 Webster]

   2. Slow in progress; tardy. " No motion so swift or languid."
      --Bentley.
      [1913 Webster]

   3. Promoting or indicating weakness or heaviness; as, a
      languid day.
      [1913 Webster]

            Feebly she laugheth in the languid moon. --Keats.
      [1913 Webster]

            Their idleness, aimless flirtations and languid
            airs.                                 --W. Black.

   Syn: Feeble; weak; faint; sickly; pining; exhausted; weary;
        listless; heavy; dull; heartless. -- Lan"guid*ly, adv.
        -- Lan"guid*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

languid
    adj 1: lacking spirit or liveliness; "a lackadaisical attempt";
           "a languid mood"; "a languid wave of the hand"; "a hot
           languorous afternoon" [syn: dreamy, lackadaisical,
           languid, languorous]