Earth & SkyGreek → English
Gnomon
/ˈnoʊmɒn/noun
The rod or triangular plate of a sundial, whose shadow marks the hour.
The Greek roots
γνώμων
gnṓmōn
one who knows, indicator
γιγνώσκω
gignṓskō
to know, perceive
Literally: “the knower”
The story of the word
Herodotus says plainly that the Greeks took the gnomon and the twelve-part day from the Babylonians, one of the few times a Greek writer admits borrowing outright. Euclid uses the same word for a different indicator, the L-shaped piece left when a square is cut from the corner of a bigger square. To work properly the rod must be tilted to the local latitude and pointed at the celestial pole, so a sundial carried north or south stops telling the truth.
- How it travelled
- Ancient Greek → Latin → English
- First recorded
- 16th century
Same family
diagnosisprognosisagnosticphysiognomy
In a sentence
The garden dial reads an hour fast in summer because nobody told the gnomon about daylight saving.