# Horologium

> English word · Proper noun

## Definitions
1. Synonym of Tower of the Winds, a monument in ancient Athens that included a clepsydra and multiple prominent sundials.
2. Synonym of Solarium, a monument in ancient Rome whose obelisk was once believed to have acted as a sundial gnomon.
3. A constellation of the southern sky, said to resemble a pendulum clock. It lies between the constellations Fornax and Dorado.
4. Alternative letter-case form of horologium, the book of hours in the Eastern Orthodox and Catholic churches.

## Etymology
See horologium. As a location in Rome, a clipping of Latin Hōrologium Augustī (“Sundial of Augustus”). As a constellation, a clipping of Latin Hōrologium Oscillitorium (“Pendulum Clock”), coined in 1763 by the French astronomer De Lacaille to honor the Dutch astronomer and mathematician Christian Huygens, who had written a major work by that name.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/horologium