heliogram

9.9

A message sent using sunlight and a mirror to make flashes

noun
/ˈhiːliəˌɡræm/

Archaic

: heliograma

In the 19th century, sending a heliogram was an effective way to transmit messages over long distances.

Examples

The explorers used a heliogram to signal their location to the base camp.
The scout sent a heliogram to the base camp.
A single flash of a heliogram could be seen from miles away on a clear day.
They received a heliogram from the mountain top.
In the 19th century, sending a heliogram was an effective way to transmit messages over long distances.
A single flash of a heliogram could be seen from miles away on a clear day.
The explorers used a heliogram to signal their location to the base camp.

Synonyms

radiogram

vsheliogram

Archaic

1 8.3

A message sent by radio to people far away

uses reflected sunlight and a mirror rather than radio waves to communicate

Surface Forms

heliogram singular

heliograms plural

Morphology

heliogram = helio + gram

Built from the combining forms helio- ('sun') and -gram ('written/record'); the components occur in technical vocabulary so the meaning is partly guessable but not fully transparent to an average B1 learner.

Etymology

Heliogram comes from Greek parts heli- meaning 'sun' and -gram meaning 'something written', the same -gram you see in telegram. So a heliogram is literally a 'sun-written' message, which is why it means a message sent by reflecting sunlight, often with a mirror.