Lacking compassion; without sympathy or concern for the suffering of others.
From compassion (Latin com- 'with' + pati 'to suffer') + -less suffix meaning 'without'. The suffix -less has been used in English since Old English times to negate qualities.
Interestingly, 'compassionless' is rarely used compared to 'cold-hearted' or 'cruel'—our language gravitates toward more evocative words when describing lack of empathy, suggesting we find compassion so important we've created multiple vocabulary routes to criticize its absence.
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