from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The condition of being calloused.
  • noun Hardheartedness; insensitivity.

from The Century Dictionary.

  • noun The state or quality of being hardened or callous.
  • noun In a concrete sense, any thickened or hardened part on the surface of the human body or that of any animal, such as the hard and often somewhat bony lumps that arise in places exposed to constant pressure and friction, the cicatrized surfaces of old ulcers or wounds, etc., the natural cutaneous thickenings on the buttocks of gibbons and other monkeys, etc.
  • noun In botany, any part of a plant unusually hard.
  • noun In entomology, an elevated, rounded portion of the surface, generally smooth, and paler than the surrounding parts, appearing like a swelling.

from the GNU version of the Collaborative International Dictionary of English.

  • noun A hard or thickened spot or protuberance; a hardening and thickening of the skin or bark of a part, eps. as a result of continued pressure or friction.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun countable A callus
  • noun uncountable A callous demeanour; insensitivity or hardheartedness

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun devoid of passion or feeling; hardheartedness
  • noun an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English callosite, from Old French, from Late Latin callōsitās, from Latin callōsus, callous; see callous.]



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  • Also used to describe the raised skin on Right Whales that appears white/yellow due to whale lice. Marine scientists use the callosities to identify different whales for tracking and observational studies.

    June 17, 2008