How did fathom originate?: Information Roundup
Fathom in the sense of a unit of measurement is derived from Anglo-Saxon feathm, "an embrace." The outstretched arms are the underlying thought of the term. Before linear measurements were standardized and when most of them were derived from the human body, a fathom was a rough measurement of the distance from finger tips to finger tips of a man's outstretched arms. Fathom is used in the English version of the New Testament to render Greek origina, which is from orego, signifying to extend the arms. Although originally a land term, fathom as a noun survives chiefly as a sea term to denote six feet, the unit of measure used in taking soundings of the depth of water. Figuratively the word is used in the sense of to sound, to interpret, to get at the bottom of or to find the depth of.