Fellow is an old fashioned word for “guy.” If you’re wearing a top hat, you may address someone as “my good fellow.” It’s also a non-stuffy word to describe people in the same situation, such as you and your fellow Vocabulary.com fans.
Other words for fellow include "chap" and "dude." A fellow can also be someone’s boyfriend, as in “Is he your fellow?” an interested suitor might ask. Another kind of fellow is an academic who's either reached a high position or won a prestigious scholarship. A MacArthur Fellow, for example, is a person who won a MacArthur fellowship (a well-deserved hunk of money). Fellow comes from an Old English word, feolaga, "one who shares with another."