This is the 7965th most frequent Japanese word.
大井
"大井" (Ōi) is a Japanese proper noun often used as a place name or surname, meaning "large well."
Here, '大井' is used as part of a place name, 'Ōimachō'.
大井町は東京にあります。
Ōimachō is located in Tokyo.
In this example, '大井' refers to the name of a racecourse, demonstrating its use in a specific proper noun.
大井競馬場でイベントが開催されます。
An event is taking place at Ōi Racecourse.
In this sentence, '大井' is utilized metaphorically to describe the great capability of an object.