"Overswarmed" is a word that is not commonly used, but its meaning is relatively easy to deduce. The phonetic transcription of this word is /ˌoʊvərˈswɔrmd/, and it is spelled by simply adding the prefix "over-" to the verb "swarm". "Swarm" means to gather or move in large numbers, so "overswarmed" would mean being overwhelmed by a large number of something. While it may not be a common word, its meaning can help to express a feeling of being overrun or crowded.