A group of birds, sheep, or other animals moving together; also a tuft of hair or fiber.
From Old English 'flocc' and Old Norse 'flokkr.' Originally meant a crowd of people or animals, later applied specifically to birds flying together. The fiber meaning is separate, from Latin 'floccus' meaning tuft.
A flock is fascinating because the animals don't have a leader—each bird follows simple rules about staying close to neighbors, and suddenly you get this coordinated movement. That's why computer scientists use 'flocking algorithms' to animate crowds.
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