Source : Webster's Revised Unabridged Dictionary (1913)

Jowl \Jowl\, n. [For older chole, chaul, AS. ceaft jaw. Cf.
   {Chaps}.]
   The cheek; the jaw. [Written also {jole}, {choule}, {chowle},
   and {geoule}.]

   {Cheek by jowl}, with the cheeks close together; side by
      side; in close proximity. ``I will go with three cheek by
      jole.'' --Shak. `` Sits cheek by jowl.'' --Dryden.

Cheek \Cheek\ (ch[=e]k), n. [OE. cheke, cheoke, AS. ce[`a]ce,
   ce[`o]ce; cf. Goth. kukjan to kiss, D. kaak cheek; perh. akin
   to E. chew, jaw.]
   1. The side of the face below the eye.

   2. The cheek bone. [Obs.] --Caucer.

   3. pl. (Mech.) Those pieces of a machine, or of any timber,
      or stone work, which form corresponding sides, or which
      are similar and in pair; as, the cheeks (jaws) of a vise;
      the cheeks of a gun carriage, etc.

   4. pl. The branches of a bridle bit. --Knight.

   5. (Founding) A section of a flask, so made that it can be
      moved laterally, to permit the removal of the pattern from
      the mold; the middle part of a flask.

   6. Cool confidence; assurance; impudence. [Slang]

   {Cheek of beef}. See Illust. of {Beef}.

   {Cheek bone} (Anat.) the bone of the side of the face; esp.,
      the malar bone.

   {Cheek by jowl}, side by side; very intimate.

   {Cheek pouch} (Zo["o]l.), a sacklike dilation of the cheeks
      of certain monkeys and rodents, used for holding food.

   {Cheeks of a block}, the two sides of the shell of a tackle
      block.

   {Cheeks of a mast}, the projection on each side of a mast,
      upon which the trestletrees rest.

   {Cheek tooth} (Anat.), a hinder or molar tooth.

   {Butment cheek}. See under {Butment}.

Source : WordNet®

cheek by jowl
     adv : in close proximity; "the houses were jumbled together cheek
           by jowl"