The Collaborative International Dictionary of English v.0.48:

Purl \Purl\, n.
   1. An embroidered and puckered border; a hem or fringe, often
      of gold or silver twist; also, a pleat or fold, as of a
      band.
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            A triumphant chariot made of carnation velvet,
            enriched withpurl and pearl.          --Sir P.
                                                  Sidney.
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   2. An inversion of stitches in knitting, which gives to the
      work a ribbed or waved appearance.
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   Purl stitch. Same as Purl, n., 2.
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The Collaborative International Dictionary of English v.0.48:

Stitch \Stitch\, n. [OE. stiche, AS. stice a pricking, akin to
   stician to prick. See Stick, v. i.]
   1. A single pass of a needle in sewing; the loop or turn of
      the thread thus made.
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   2. A single turn of the thread round a needle in knitting; a
      link, or loop, of yarn; as, to let down, or drop, a
      stitch; to take up a stitch.
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   3. [Cf. OE. sticche, stecche, stucche, a piece, AS. stycce.
      Cf. Stock.] A space of work taken up, or gone over, in a
      single pass of the needle; hence, by extension, any space
      passed over; distance.
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            You have gone a good stitch.          --Bunyan.
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            In Syria the husbandmen go lightly over with their
            plow, and take no deep stitch in making their
            furrows.                              --Holland.
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   4. A local sharp pain; an acute pain, like the piercing of a
      needle; as, a stitch in the side.
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            He was taken with a cold and with stitches, which
            was, indeed, a pleurisy.              --Bp. Burnet.
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   5. A contortion, or twist. [Obs.]
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            If you talk,
            Or pull your face into a stitch again,
            I shall be angry.                     --Marston.
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   6. Any least part of a fabric or dress; as, to wet every
      stitch of clothes. [Colloq.]
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   7. A furrow. --Chapman.
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   8. An arrangement of stitches, or method of stitching in some
      particular way or style; as, cross-stitch; herringbone
      stitch, etc.
      [Webster 1913 Suppl.]

   Chain stitch, Lock stitch. See in the Vocabulary.

   Pearl stitch, or Purl stitch. See 2nd Purl, 2.
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WordNet (r) 3.0 (2006):

purl stitch
    n 1: a basic knitting stitch [syn: purl, purl stitch]
    v 1: make with purl stitches