The Collaborative International Dictionary of English v.0.48:

Atlas \At"las\, n.; pl. Atlases. [L. Atlas, -antis, Gr. ?, ?,
   one of the older family of gods, who bears up the pillars of
   heaven; also Mt. Atlas, in W. Africa, regarded as the pillar
   of heaven. It is from the root of tlh^nai to bear. See
   Tolerate.]
   1. One who sustains a great burden.
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   2. (Anat.) The first vertebra of the neck, articulating
      immediately with the skull, thus sustaining the globe of
      the head, whence the name.
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   3. A collection of maps in a volume;

   Note: supposed to be so called from a picture of Atlas
         supporting the world, prefixed to some collections.
         This name is said to have been first used by Mercator,
         the celebrated geographer, in the 16th century.
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   4. A volume of plates illustrating any subject.
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   5. A work in which subjects are exhibited in a tabular from
      or arrangement; as, an historical atlas.
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   6. A large, square folio, resembling a volume of maps; --
      called also atlas folio.
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   7. A drawing paper of large size. See under Paper, n.
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   Atlas powder, see Atlas powder in the vocabulary; a
      blasting compound containing nitroglycerin.
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