know by sight

know (someone or something) by sight

To recognize someone or something based on its or their appearance, but without knowing its or their name or any other information. Everyone in town knows the iconic bridge by sight, but few know the history of when it was built and why it was designed to look so peculiar. Even after working there for a year, there were still some co-workers whom I only knew by sight.

See also: by, know, sight

know someone by sight

to recognize a person's face, but not know the name. I'm afraid I don't know her by sight. I know all my employees by sight.

See also: by, know, sight

know by sight

Recognize someone or something by appearance but not know the name or other details. For example, I know a lot of people by sight from the tennis courts. [1200s]

See also: by, know, sight