One frequent error that writers make involves homophones, or different words that sound the same when spoken. Anyone who has ever had to choose the correct option between poor, pour, and pore can surely relate.
Another homophone quandary involves the words callous and callus.
History of Both Words
Choosing the wrong word from this pair is easy, but you can easily avoid the mistake with a bit of information:
- According to the Merriam-Webster dictionary, callous is an adjective meaning “being hardened and thickened.”
- Callus is a noun that means “a thickening of or a hard thickened area on skin or bark.”
There’s little reason that callus and callous should exist as separate words, especially given their origins. According to the Oxford English Dictionary, these words have similar language histories. They both emerged during the Middle Ages, and both stem from the Latin word for hard skin, callum.
Between the two homophones, callous arrived on the scene first. The OED says that its first known use was about 1400. At the time, callous pertained to animal tissue that was “hardened, thickened” and had a hornlike layer called stratum corneum. Animal tissue would become callous through “repeated friction or pressure.” Callous skin had calluses.
Even so, the noun callus would not come into common usage until 1563. It referred to a hard or thickened layer of skin, specifically the aforementioned stratum corneum. The phrasing of both words’ definitions was virtually identical.
From Literal to Figurative
Over time, callous and callus developed figurative meanings relating to the same emotion and social state. Both words referred to lacking feeling or empathy.
Each word had a particular character during this time. Around 1647, calling someone callous meant they were hard, unfeeling, and not easily affected emotionally. It also indicated that the person showed a disregard for other people’s feelings and welfare.
In 1683, the word callus had a figurative meaning as “hardened” or “thickened,” concerning emotions and character. You could consider this a symbolic understanding of the callus as a hard layer of skin caused by repeated by enduring injury or friction.
Also of note, during this time, both callus and callous could be used as verbs.
Often Confused and Sometimes Interchangeable
These similar histories and definitions led to confusion, and plenty of people have publicly mistaken callus and callous. In the 1990s, the Dr. Scholl’s foot care company made such an error, marketing one of their callus-removing products as “callous removers.” This widely distributed mistake undoubtedly led to further confusion.
While callus and callous rarely get inverted in the news, spell checkers have it easier in the United Kingdom. In British spelling, callous is an acceptable spelling for callus.
A Unique Pair of Words
The question remains, why do callus and callous still exist as two separate words in our vocabulary? The poor/pore/pour example mentioned earlier has a heterographic relationship: all three words sound the same but have different meanings. Conversely, callus and callous sound identical, but their definitions are practically identical also. Both words mean “hardened,” though callus is a noun and callous is an adjective.
Nor is the difference between these two spellings attributable to local style, as you can attribute some variations like honor/honour or councilor/counselor. Further, this isn’t a dichotomy like disc and disk, where the difference depends on one spelling for devices (e.g., compact discs) and another spelling for computer drives and human anatomy (e.g., hard disk drives and herniated disks).
What would you call two same-sounding words with identical etymologies and similar meanings like callus and callous? Such a specific term might not exist, but surely other word pairs fall into this category. It seems downright callous not to give them a name.
Related: We here at businesswritingblog love similar sounding words! Here are a few of our favorites: Apart vs. A part, Compliment vs. Complement, Whether or Weather (or wether!)
