The Collaborative International Dictionary of English v.0.48:

Phalanx \Pha"lanx\, n.; pl. Phalanxes, L. Phalanges. [L.,
   from Gr. fa`lagx.]
   1. (Gr. Antiq.) A body of heavy-armed infantry formed in
      ranks and files close and deep. There were several
      different arrangements, the phalanx varying in depth from
      four to twenty-five or more ranks of men. "In cubic
      phalanx firm advanced." --Milton.
      [1913 Webster]

            The Grecian phalanx, moveless as a tower. --Pope.
      [1913 Webster]

   2. Any body of troops or men formed in close array, or any
      combination of people distinguished for firmness and
      solidity of a union.
      [1913 Webster]

            At present they formed a united phalanx. --Macaulay.
      [1913 Webster]

            The sheep recumbent, and the sheep that grazed,
            All huddling into phalanx, stood and gazed.
                                                  --Cowper.
      [1913 Webster]

   3. A Fourierite community; a phalanstery.
      [1913 Webster]

   4. (Anat.) One of the digital bones of the hand or foot,
      beyond the metacarpus or metatarsus; an internode.
      [1913 Webster]

   5. [pl. Phalanges.] (Bot.) A group or bundle of stamens, as
      in polyadelphous flowers.
      [1913 Webster]