The Collaborative International Dictionary of English v.0.48:

Livelong \Live"long`\, a. [For lifelong. Cf. Lifelong.]
   1. Whole; entire; long in passing; -- used of time, as day or
      night, in adverbial phrases, and usually with a sense of
      tediousness.
      [1913 Webster]

            The obscure bird
            Clamored the livelong night.          --Shak.
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            How could she sit the livelong day,
            Yet never ask us once to play?        --Swift.
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   2. Lasting; durable. [Obs.]
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            Thou hast built thyself a livelong monument.
                                                  --Milton.
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WordNet (r) 3.0 (2006):

livelong
    adj 1: (of time) constituting the full extent or duration; "all
           the livelong day"
    n 1: perennial northern temperate plant with toothed leaves and
         heads of small purplish-white flowers [syn: orpine,
         orpin, livelong, live-forever, Sedum telephium]