Source : Webster's Revised Unabridged Dictionary (1913)

Darn \Darn\, n.
   A place mended by darning.

Darn \Darn\, v. t.
   A colloquial euphemism for {Damn}.

Darn \Darn\, v. t. [imp. & p. p. {Darned}; p. pr. & vb. n.
   {Darning}.] [OE. derne, prob. of Celtic origin; cf. W. darnio
   to piece, break in pieces, W. & Arm. to E. tear. Cf. {Tear},
   v. t.]
   To mend as a rent or hole, with interlacing stitches of yarn
   or thread by means of a needle; to sew together with yarn or
   thread.

         He spent every day ten hours in his closet, in darning
         his stockins.                            --Swift.

   {Darning last}. See under {Last}.

   {Darning needle}.
   (a) A long, strong needle for mending holes or rents,
       especially in stockings.
   (b) (Zo["o]l.) Any species of dragon fly, having a long,
       cylindrical body, resembling a needle. These flies are
       harmless and without stings.

   Note: [In this sense, usually written with a hyphen.] Called
         also {devil's darning-needle}.

Source : WordNet®

darn
     n 1: a euphemism for `damn'
     2: something of little value; "his promise is not worth a
        damn"; "not worth one red cent"; "not worth shucks" [syn:
        {damn}, {hoot}, {red cent}, {shit}, {shucks}, {tinker's
        damn}, {tinker's dam}]
     3: sewing or darning that repairs a worn or torn hole
        (especially in a garment); "her stockings had several
        mends" [syn: {mend}, {patch}]
     v : repair by sewing; "darn socks"