TOEIC Link Part 5: callous versus callus
Callous and callus come from the same Latin idea of hardening and sound almost identical, but they work as different parts of speech. Callous is an adjective meaning emotionally hardened, insensitive, or unfeeling. Callus is a noun naming a patch of thickened, toughened skin. Part 5 places them where either spelling could look right, so it checks whether you mean an unfeeling attitude or a physical thickening. For the wider set of look-alike traps, start with the commonly confused word pairs master index.
The core rule: unfeeling versus thickened skin
- callous (adjective) = insensitive, hardened, uncaring. The manager's callous response upset the whole team. / Critics called the policy callous toward low-income families. It answers how did someone behave? — coldly. Link the -ous ending to other attitude adjectives like generous or anxious: callous describes a trait.
- callus (noun) = a hardened, thickened area of skin. Years of guitar practice left a callus on each fingertip. / The runner developed a callus on her heel. It answers what formed on the body? — thick skin. Link the -us ending to concrete Latin nouns like focus or radius: a callus is a thing you can point to.
The endings do the memory work: -ous marks the adjective (a describing word, like famous); -us marks the noun (a naming word, like bonus). One describes a cold attitude; the other names a lump of skin.
Why Part 5 likes this pair
Part of speech separates them. If the blank needs a word to describe a person, tone, or decision, you need the adjective callous. If the blank needs a noun naming something on the skin, you need callus.
Ignoring the complaints was a __ decision that damaged morale.
A word describing the decision needs the adjective callous.
The heavy tools gradually formed a thick __ on his palm.
A noun naming the thickened skin needs callus.
Spotting the clue
Decide whether the sentence needs a describing word or a naming word:
- Does the blank describe someone as unfeeling? → choose callous (a callous remark).
- Does the blank name a patch of hard skin? → choose callus (a callus on the thumb).
A quick test: can you replace the word with "insensitive" and keep the meaning? Then it is the adjective callous. Can you put "a" or "the" in front and count it? Then it is the noun callus. When the sentence rates an attitude, lean callous; when it points to something on the body, lean callus. For more sound-alike adjectives that hide in Part 5, see the adjective and adverb confusable pairs study guide.