Many
Much, Lots Of
い adjective
This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of many? It is also many (or you could say much). Speaking of which, there are so many kanji to learn, ammiright?
おおい
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
Think of something that is many. Doesn't matter what it is as long as you imagine a ridiculous number of them. Many of them. So many that they start avalanching into you and crushing you. The last thing you yell is "おお!!!" as you get smushed.
このりょうりは多すぎます。
There is too much food.
「自分は正しい」とおもいこんでいる人は多い。
There are many people who firmly believe that they are right.
電車にはとても多くの乗客が乗っていたので、眠ることはできなかったが、大声で歌うことはできた。
I wasn’t able to sleep because there were far too many people on the train, so I just sang loudly instead.