From Longman Dictionary of Contemporary Englishsundialsun‧dial /ˈsʌndaɪəl/ noun [countable] 
TMDLOan object used in the past for telling the time. The shadow of a pointed piece of metal shows the time and moves round as the sun moves.
TMDLOan object used in the past for telling the time. The shadow of a pointed piece of metal shows the time and moves round as the sun moves.Examples from the Corpus
sundial• Sundial stolen A 30-INCH sundial, valued at £500, was stolen from a garden in Upper Froyle on Friday night.• Based in Washington state, Torrens also makes birdbaths, sprinklers and sundials from recycled industrial materials.• That's what I enjoy doing, making sundials. 