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definitions

didactylism

[dī-dăk′tə-lĭz′əm]
n.
  1. A congenital defect in which there are only two digits on a hand or a foot.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.