know by sight

know (someone or something) by sight

To recognize someone or something based solely on appearance (without knowing any other information, such as a name, etc.). Even after working there for a year, there were still some co-workers I only knew by sight. I'd know the place by sight, but I don't think I could tell you how to get there.

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