- an instrument with mirrors and a shutter used for sending messages in Morse code by reflecting the sun's rays
- a device used to photograph the sun
WordReference Random House Unabridged Dictionary of American English © 2026
he•li•o•graph
(hē′lē ə graf′, -gräf′),USA pronunciation n.
v.t., v.i.
he•li•og•ra•pher
(hē′lē og′rə fər),USA pronunciation n.
he•li•o•graph•ic
(hē′lē ə graf′ik),USA pronunciation he′li•o•graph′i•cal, adj.
he′li•o•graph′i•cal•ly, adv.
he′li•og′ra•phy, n.
- Opticsa device for signaling by means of a movable mirror that reflects beams of light, esp. sunlight, to a distance.
- Astronomyphotoheliograph.
- Meteorologyan instrument for recording the duration and intensity of sunshine.
- Photography, Printingan early type of photoengraving made on a metal plate coated with sensitized asphalt.
v.t., v.i.
- to communicate by heliograph.
- 1815–25; helio- + -graph
he′li•og′ra•phy, n.
Collins Concise English Dictionary © HarperCollins Publishers::
heliograph /ˈhiːlɪəʊˌɡrɑːf; -ˌɡræf/ n
'heliograph' also found in these entries (note: many are not synonyms or translations):