Teem in is a phrase that is commonly used when describing a situation where a large number of people or things are present in a particular place or area. There are several synonyms for the word 'teem in', including to swarm, to crowd, to inundate, to overflow, to throng, and to permeate. Each of these words can be used to convey the same meaning as teem in and are ideal for describing a crowded event, a busy marketplace, a packed theater, or a bustling city. Whether you choose to use teem in or one of its synonyms, you can be sure that you will effectively paint a vivid and descriptive picture of the situation at hand.