The Collaborative International Dictionary of English v.0.48:

Darn \Darn\, n.
   A place mended by darning.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Darn \Darn\, v. t.
   A colloquial euphemism for Damn.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Darn \Darn\ (d[aum]rn), v. t. [imp. & p. p. Darned
   (d[aum]rnd); 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.
   [1913 Webster]

         He spent every day ten hours in his closet, in darning
         his stockings.                           --Swift.
   [1913 Webster]

   Darning last. See under Last.

   Darning needle.
   (a) A long, strong needle for mending holes or rents,
       especially in stockings.
   (b) (Zool.) 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.
         [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "darn":
   absolute, accurse, anathematize, blamed, blankety-blank, blaspheme,
   blast, blasted, blessed, cobble, commission, condition, confound,
   confounded, curse, cursed, cussed, damn, do up, doctor, doggone,
   downright, excommunicate, execrate, fix, fix up, fulminate against,
   hex, imprecate, infernal, mend, outright, overhaul, patch,
   patch up, positive, put in commission, put in order, put in repair,
   put in shape, ready, recap, recondition, repair, retread, service,
   set to rights, sew up, straight-out, throw a whammy,
   thunder against, tinker, tinker up, unmitigated