English
siriometer
From Sirius + -o- + meter.
The story
It is roughly twice the distance from Earth to the star Sirius.
Today it means
noun A unit of distance equal to one million astronomical units or 15.813 light-years.
Sources
Sources: Wiktionary, “siriometer”. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.
Etymograph / siriometer