noun
sea of people; huge crowd
Often used in the compound 人海戦術 (human-wave tactics) or to describe a vast, overwhelming crowd. As a standalone noun, it is somewhat literary.
See also: 人海戦術
駅前は人海でごった返していた。
The area in front of the station was jammed with a sea of people.
人海戦術で問題を解決しようとした。
They tried to solve the problem by using human-wave tactics.