Approximately this height. Said while using one's fingers, hands, or arms to visibly demonstrate size. "I'll have a small glass of wine, only yay tall," he said, holding his thumb and index finger about an inch and a half apart. "Fish have to be about yay tall for you to keep them," she said, putting her hand up to her sternum. A: "You were only yay tall the last time I saw you!" B: "I was 11, Uncle Jerry. There's no way I was only up to your hip."
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.