Formal or literary noun meaning a very large number of people or things. Often used in written language or formal speech.
衆多の参加者が会議に集まった。
A multitude of participants gathered at the conference.
その問題については衆多の意見がある。
There are a great many opinions on that issue.
Compound of 衆 (many, multitude) and 多 (many). The exact historical derivation is uncertain, but the combination reinforces the meaning of a large quantity.