heliograph

/ˈhiː.li.əˌɡɹæf/

Etymology

From helio- + -graph.

Why this word is great

HELIOGRAPH — [Noun] An apparatus for signaling by reflecting sunlight with a movable mirror. From the Greek helios ("sun") and graphein ("to write"), it is sunlight given language. Unlike "telegraph" (which hums through copper veins) or "semaphore" (which flaps like a mechanical bird), the heliograph is silent, swift, and weightless. It is the glint of a mirror in a soldier’s hand, the sudden flare on a distant ridge, the ephemeral Morse code of a sunbeam flickering across miles—proof that even the brightest light can be bent to human will, if only for a moment.

noun

An apparatus for signalling by means of a moveable mirror which reflects flashes of sunlight.“Now Jones had left his new-wed bride to keep his house in order, / And hied away to the Hurrum Hills above the Afghan border, / To sit on a rock with a heliograph; but ere he left he taught / His wife the working of the Code that sets the miles at naught. / And Love had made him very sage, as Nature made her fair; / So Cupid and Apollo linked, per heliograph, the pair.”
A heliogram.
An instrument for measuring the intensity of sunlight.
A device for photographing the sun.
A photograph.

verb

To send a message by heliograph.“With damnatory dot and dash he heliographed his wife / Some interesting details of the General's private life.”
To send a heliograph.
To photograph by sunlight.