CALLUS definition and meaning | Collins English Dictionary (2025)

COBUILD frequency band

callus

(kæləs )

Word forms: plural calluses

countable noun

A callus is an unwanted area of thick skin, usually on the palms of your hands or the soles of your feet, which has been caused by something rubbing against it.

There are no split nails or calluses here.

callus in British English

(ˈkæləs )

nounWord forms: plural -luses

1. 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

3. botany

a mass of hard protective tissue produced in woody plants at the site of an injury

an accumulation of callose in the sieve tubes

4. biotechnology

a mass of undifferentiated cells produced as the first stage in tissue culture

verb

to produce or cause to produce a callus

Word origin

C16: from Latin, variant of callum hardened skin

COBUILD frequency band

callus in American English

(ˈkæləs )

nounWord forms: plural ˈcalluses

a hardened, thickened place on the skin

the hard substance that forms at the break in a fractured bone and serves to reunite the parts

a disorganized mass of cells that develops over cuts or wounds on plants, as at the ends of stem or leaf cuttings

verb intransitive, verb transitive

to develop or cause to develop a callus

Word origin

L, var. of callum, hard skin

COBUILD frequency band

callus in American English

(ˈkæləs) (noun plural -luses, verb -lused, -lusing)

noun

1. Pathology & Physiology

a hardened or thickened part of the skin; a callosity

a new growth of osseous matter at the ends of a fractured bone, serving to unite them

2. Also: callose Botany

the tissue that forms over the wounds of plants, protecting the inner tissues and causing healing

a deposit on the perforated area of a sieve tube

c.(in grasses)

a tough swelling at the base of a lemma or palea

intransitive verb

to form a callus

transitive verb

to produce a callus or calluses on

Heavy work callused my hands

Word origin

[1555–65; ‹ L callus, masc. var. of callum; see callous]

Examples of 'callus' in a sentence

callus

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The inner lip can sometimes show a deep callus, and in many cases this extends over the parietal wall to the end of the aperture.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Olivella_(gastropod)

The parietal callus usually covers more than half the surface of the base.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Astralium_tentoriiforme

Aperture obliquely ovate, occupying about half the length of the shell, covered with a slight callus deposit far within, not quite obscuring the external coloration.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Paramelania_damoni

Spores amygdaliform to sublimoniform, thick-walled, epitunica strongly developed with cavernous type of ornamentation, with a conspicuous callus and without germ-pore.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Anamika_(fungus)

The inner lip has a slight callus transparent.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Harpa_fulvomichaelensis

Further, moss protoplasts do not need phytohormones for regeneration, and they do not form a callus.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Somatic_fusion

Differences of auxin sensitivity in embryogenic callus growth between different genotypes of the same species show how variable auxin responses can be.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Somatic_embryogenesis

Cells derived from competent source tissue are cultured to form an undifferentiated mass of cells called a callus.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Plant_embryogenesis

The columellar callus has a characteristic faint silvery gloss.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Lentigo_lentiginosus

Specific auxin to cytokinin ratios in plant tissue culture medium give rise to an unorganized growing and dividing mass of callus cells.

Retrieved from Wikipedia CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/. Source URL: https://en.wikipedia.org/wiki/Callus_(cell_biology)