The Collaborative International Dictionary of English v.0.48:

Whelk \Whelk\, n. [OE. whelke, dim. of whele. See Wheal a
   pustule.]
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   1. A papule; a pustule; acne. "His whelks white." --Chaucer.
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   2. A stripe or mark; a ridge; a wale.
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   Chin whelk (Med.), sycosis.

   Rosy whelk (Med.), grog blossom.
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