Fathom

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. 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. There are two yards (6 feet) in an imperial fathom. Originally the span of a man's outstretched arms, the size of a fathom has varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Formerly, the term was used for any of several units of length varying around 5–5 1⁄2 feet (1.5–1.7 m). The name derives from the Old English word fæðm, cognate to the Danish (via the Vikings) word 'favn' meaning embracing arms or a pair of outstretched arms., cognate maybe also via the Old High German word 'fadum' of the same meaning. In Middle English it was fathme. 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).