This is the 1406th most frequent Japanese word.
大使
Ambassador.
In this sentence, '大使' refers to an official representative or diplomat sent by a country to represent it in another country.
彼は日本の大使として海外で働いています。
He works overseas as an ambassador of Japan.
Here, '大使' forms part of the compound word '大使館', which means 'embassy', indicating the location associated with ambassadors.
大使館で働くことは面白そうですね。
Working at an embassy seems interesting, doesn't it?
In this example, '大使' is used to signify individuals taking on the symbolic role of an ambassador in a simulated or educational setting.