[ kal-uh s ]
/ ˈkæl əs /

noun, plural cal·lus·es.

Pathology, Physiology.
  1. a hardened or thickened part of the skin; a callosity.
  2. a new growth of osseous matter at the ends of a fractured bone, serving to unite them.
Also callose. Botany.
  1. the tissue that forms over the wounds of plants, protecting the inner tissues and causing healing.
  2. a deposit on the perforated area of a sieve tube.
  3. (in grasses) a tough swelling at the base of a lemma or palea.

verb (used without object), cal·lused, cal·lus·ing.

to form a callus.

verb (used with object), cal·lused, cal·lus·ing.

to produce a callus or calluses on: Heavy work callused his hands.

Origin of callus

1555–65; < Latin callus, masculine variant of callum; see callous


un·cal·lused, adjective


callous callus Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for callus

British Dictionary definitions for callus

/ (ˈkæləs) /

noun plural -luses

Also called: callosity an area of skin that is hard or thick, esp on the palm of the hand or sole of the foot, as from continual friction or pressure
an area of bony tissue formed during the healing of a fractured bone
  1. a mass of hard protective tissue produced in woody plants at the site of an injury
  2. an accumulation of callose in the sieve tubes
biotechnology a mass of undifferentiated cells produced as the first stage in tissue culture


to produce or cause to produce a callus

Word Origin for callus

C16: from Latin, variant of callum hardened skin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for callus

[ kăləs ]

n. pl. cal•lus•es

The hard bony tissue that develops around the ends of a fractured bone during healing.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for callus

[ kăləs ]

An area of the skin that has become hardened and thick, usually because of prolonged pressure or rubbing.
The hard bony tissue that develops around the ends of a fractured bone during healing.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.