<p><strong>noun</strong></p><ul><li>Plural: cal·lus·es</li><li>A hardened or thickened part of the skin; a callosity.</li><li>A new growth of osseous matter at the ends of a fractured bone, serving to unite them.</li><li>(Also Botany) The tissue that forms over the wounds of plants, protecting the inner tissues and causing healing.</li><li>A deposit on the perforated area of a sieve tube.</li><li>(In grasses) A tough swelling at the base of a lemma or palea.</li></ul><p><strong>verb</strong></p><ul><li>(Used without object) cal·lused, cal·lus·ing - to form a callus.</li><li>(Used with object) cal·lused, cal·lus·ing - to produce a callus or calluses on: Heavy work callused his hands.</li></ul>