1. [n]  a tall cylindrical vertical upright
2. [n]  a vertical structure standing alone and not supporting anything (as a monument or a column of air)
3. [n]  a fundamental principle or practice; "science eroded the pillars of superstition"
4. [n]  a prominent supporter; "he is a pillar of the community"
5. [n]  anything tall and thin approximating the shape of a column or tower; "the test tube held a column of white powder"; "a tower of dust rose above the horizon"; "a thin pillar of smoke betrayed their campsite"

1. \Pil"lar\, n. [OE. pilerF. pilier, LL. pilare, pilarium,
   pilarius, fr. L. pila a pillar. See {Pile} a heap.]
   1. The general and popular term for a firm, upright,
      insulated support for a superstructure; a pier, column, or
      post; also, a column or shaft not supporting a
      superstructure, as one erected for a monument or an
      ornament.
   
            Jacob set a pillar upon her grave.    --Gen. xxxv.
                                                  20.
   
            The place . . . vast and proud, Supported by a
            hundred pillars stood.                --Dryden.
   
   2. Figuratively, that which resembles such a pillar in
      appearance, character, or office; a supporter or mainstay;
      as, the Pillars of Hercules; a pillar of the state. ``You
      are a well-deserving pillar.'' --Shak.
   
            By day a cloud, by night a pillar of fire. --Milton.
   
   3. (R. C. Ch.) A portable ornamental column, formerly carried
      before a cardinal, as emblematic of his support to the
      church. [Obs.] --Skelton.
   
   4. (Man.) The center of the volta, ring, or manege ground,
      around which a horse turns.
   
   {From pillar to post}, hither and thither; to and fro; from
      one place or predicament to another; backward and forward.
      [Colloq.]
   
   {Pillar saint}. See {Stylite}.
   
   {Pillars of the fauces}. See {Fauces}, 1.
   
   

2. \Pil"lar\, a. (Mach.)
   Having a support in the form of a pillar, instead of legs;
   as, a pillar drill.
   
   

used to support a building (Judg. 16:26, 29); as a trophy or memorial (Gen. 28:18; 35:20; Ex. 24:4; 1 Sam. 15:12, A.V., "place," more correctly "monument," or "trophy of victory," as in 2 Sam. 18:18); of fire, by which the Divine Presence was manifested (Ex. 13:2). The "plain of the pillar" in Judg. 9:6 ought to be, as in the Revised Version, the "oak of the pillar", i.e., of the monument or stone set up by Joshua (24:26).