多(おお)く

おおく
noun, adverb
many; much; a large number; mostly
quantity
1. many; much; a large number; the majority
A large number or amount of something. Functions as a noun, often followed by の (多くの = many) or used with が/は as a subject meaning 'most' or 'the majority.'
Many people participated.
Most of the students use the train to commute to school.
In this area, it's inconvenient without a car in most cases.
被害(ひがい)を受(う)けた建物(たてもの)の多(おお)くは築(ちく)30年以上(ねんいじょう)のものだった。
Most of the damaged buildings were over 30 years old.
2. mostly; for the most part; in many cases
Used adverbially to indicate that something is true in the majority of cases.
In this area, it's inconvenient without a car in most cases.
Japanese people for the most part don't talk a lot.
I spend most of my days off at home.

The noun/adverb form of 多(おお)い (many). While 多(おお)い exists as an adjective, it cannot directly modify a noun — *多(おお)い人(ひと) is ungrammatical. Use 多(おお)くの instead.

Common patterns

Watch out

Learners often write 多(おお)い人(ひと) instead of 多(おお)くの人(ひと) or 人(ひと)が多(おお)い. This is one of the most common errors with 多(おお)い.