The Collaborative International Dictionary of English v.0.48:

Sunburn \Sun"burn`\, v. t. [imp. & p. p. Sunburnedor
   Sunburnt; p. pr. & vb. n. Sunburning.]
   To burn or discolor by the sun; to tan.
   [1913 Webster]

         Sunburnt and swarthy though she be.      --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sunburn \Sun"burn`\, n.
   The burning or discoloration produced on the skin by the heat
   of the sun; tan.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sunburn
    n 1: a browning of the skin resulting from exposure to the rays
         of the sun [syn: tan, suntan, sunburn, burn]
    2: redness of the skin caused by exposure to the rays of the sun
       [syn: sunburn, erythema solare]
    v 1: get a sunburn by overexposure to the sun [syn: sunburn,
         burn]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "sunburn":
   brand, bronze, brown, burn, embrown, infuscate, mat burn, rust,
   scald, scorch, sear, second-degree burn, singe, sunscald, suntan,
   tan, third-degree burn, windburn