A flock is a group of birds (or sometimes sheep or goats) gathered together. When you see dozens of geese flying south in their V-shaped formation for winter, that's a flock. When a farmer tends to 50 sheep grazing in a field, that's also a flock.

The word captures something important: these animals coordinate their movements. A flock moves as a unit, like when starlings swirl through the sky in huge, shifting clouds, or when chickens cluster around scattered grain. Watch a flock of pigeons in a park: when one takes off, others follow almost instantly, as if connected by invisible threads.

People also use flock as a verb meaning to gather or move in a group. Fans might flock to a stadium before a big game. Students might flock to the cafeteria when the lunch bell rings. Tourists flock to national parks in summer. The verb suggests not just movement but enthusiastic gathering, like everyone's drawn to the same place at once.

The related phrase flock together appears in the old saying “birds of a feather flock together,” meaning people with similar interests naturally group up, like how readers gravitate toward other readers or athletes hang out with other athletes.