Definition of: heliograph

(hē′lē·ə·graf′,-gräf′) noun
1. An instrument for taking photographs of the sun.
2. A photograph taken by sunlight.
3. A mirror for signaling by flashes of light.
—v.t. & v.i. To signal with a heliograph.
—he·li·og·ra·pher (hē′·lē·og′rə·fər) noun
—he′li·o·graph′ic adjective
—he′li·og′ra·phy noun