say it: KAL-uhs
callus is a noun and verb meaning "an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)". It carries 5 recorded senses.
(botany) an isolated thickening of tissue, especially a stiff protuberance on the lip of an orchid
botany
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for callus come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.