Which is the Ancient Greek measure that was equal to 1.8 m?

The Ancient Greek measure known as the orguia (Greek: ὀργυιά, orgyiá, lit. "outstretched") is usually translated as "fathom". By the Byzantine period, this unit came in two forms: a "simple orguia" (ἁπλὴ ὀργυιά, haplē orguiá) roughly equivalent to the old Greek fathom (6 Byzantine feet, c. 1.87 m) and an "imperial" (βασιλικὴ, basilikē) or "geometric orguia" (γεωμετρικὴ ὀργυιά, geōmetrikē orguiá) that was one-eighth longer (6 feet and a span, c. 2.10 m).

A fathom is a unit of length in the imperial and the U.S. customary systems equal to 6 feet (1.8288 m), used especially for measuring the depth of water. The fathom is not an International Standard (SI) unit, nor is it accepted internationally as a non-SI unit. However it is historically the most frequently employed maritime measure of depth in the English speaking world.