Crowd Of People
noun
When a person goes into a place (then another person goes into the place, and then another person and another person), that place eventually gets filled with a crowd of people.
Note that this word is more commonly written 人混み.
The reading comes from the word 人 and the kanji 込. Just keep in mind that the こ changes to ご and you'll be fine.
怖くて人込みの中に行けません。
I can't go into the middle of a crowd of people because I'm scared.
新宿駅構内を歩く時は、人込みでいつもイライラする。
When I walk inside Shinjuku Station, I always get frustrated with the crowds of people.
男はそう言うと、人込みにまぎれて消えてしまった。
After saying so, the man vanished into the crowd.