Gigametres

Part of speech: noun

Definitions

1. A unit of length equal to one billion metres, used to express very large distances in science and astronomy
2. A metric measurement of distance representing a billion metres, often applied to vast cosmic or geological scales
3. The plural measure of length equal to a thousand million metres, typically used for enormous spans such as interstellar distances

Etymology: "Gigametres" is the plural of "gigametre," a unit of length equal to a billion metres. The second half of the word is the familiar metric "metre," and the first part comes from "giga-," a prefix meaning a factor of one billion (10 to the ninth power). That prefix is built from the Greek "gigas," meaning "giant," the same word that gives English the mythological Giants of Greek legend. Scientists adopted it in the metric system as a way of marking very large quantities, so a term that once evoked monsters now simply counts in billions.