cowhand; herdsman; a boy or man who tends cows

The Cowherd in the folk tale 牛郎织女 niú​láng​zhī​nǚ, who is separated from the Weaver Girl by the Milky Way.

The star Altair; also known as 牵牛星 qiān​niú​xīng.

(slang) male prostitute; a man who provides sexual services for women.