Unlawful killings of humans with premeditation and malice, or collective noun for crows.
From Old English morthor, related to Latin mors (death). The application to crows dates to the 15th century, reflecting medieval superstitions about these birds as omens of death.
The collective noun 'murder of crows' reflects ancient beliefs about these intelligent birds as harbingers of doom, though crows actually mate for life and show remarkable problem-solving abilities. Medieval people noticed crows gathering at battlefields and connected them with human mortality.
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