heartless

Word family

• heart
  nounA2
• heartlessly
  adverbC1
• heartlessness
  nounC1
• hearten
  verbB2
• dishearten
  verbC1
• heartfelt
  adjectiveB2

Synonym discussion

Sense: adjective/1

All five words describe a lack of kindness or sympathy, but they differ in focus and intensity. 'Cruel' is the broadest term and can refer to physical or emotional harm, whether deliberate or not. 'Heartless' narrows the meaning to a cold, deliberate disregard for others' feelings — it implies that the person ought to care but does not. 'Cold-hearted' is similar but slightly less intense; it suggests emotional distance rather than active harshness. 'Merciless' is used when someone has the power to show mercy but refuses, often in competition, punishment, or negotiation. 'Unfeeling' is the least common and focuses on an absence of emotional responsiveness, not necessarily cruelty. For example, a boss who fires a loyal employee without notice is heartless; a judge who gives the maximum sentence to a first-time offender could be called merciless; a person who does not cry at a funeral might be described as cold-hearted or unfeeling.

Common collocations

Etymology

Formed in Old English from 'heorte' (heart, the organ considered the seat of emotion) and the suffix '-leas' (without, modern '-less'). The word originally meant 'spiritless or lacking courage' but shifted by the 16th century to mean 'lacking pity or human feeling' — the heart being the source of compassion, someone 'without a heart' cannot feel for others. The modern sense of deliberate cruelty emerged in the 19th century.