a walking dictionary

a walking dictionary

or

a walking encyclopedia

If you describe someone as a walking dictionary or a walking encyclopedia, you mean that they know a lot of words or facts. She raised five of us on her own and she's a walking dictionary. He was a walking encyclopedia of music, full of wit and charm. Note: People sometimes use other words instead of dictionary or encyclopedia. He's a walking database on anything relating to insurance.
See also: dictionary, walking