The crossword solution for the term 'SWARM IN' is 'CROWD'. A CROWD is a large group of people who have gathered together in one place. It can refer to a gathering of people for a specific purpose, such as a protest or a celebration, or it can simply refer to a large number of people in a public space. Crowds can also be used to describe a large number of animals, such as a swarm of bees or a flock of birds.