Callous means emotionally hardened or insensitive.
Callous comes under adjective.
Synonyms: cold, unfeeling, indifferent, insensitive, impervious.
Antonyms: sensitive, empathetic, compassionate, sympathetic.
Ravi never became calloused; he was always compassionate and sensitive to the needs of others.
Years of working with hardened criminals made the attorney callous and cynical.