sundial

Từ điển Oxford Advanced Learner 8th

sun·dial [sundial sundials] BrE [ˈsʌndaɪəl] NAmE [ˈsʌndaɪəl] noun
a device used outdoors, especially in the past, for telling the time when the sun is shining. A pointed piece of metal throws a shadow on a flat surface that is marked with the hours like a clock, and the shadow moves around as the sun moves across the sky.