fathomless

The word 'fathomless' is a transparent compound formed within English. Its first element, 'fathom', originates from the Old English concept of fæðm, which referred to the length of a person's two outstretched arms—a natural, bodily unit of measure. This concrete measurement was later standardized to six feet, specifically for sounding water depth. The suffix '-less', an ancient Germanic formative meaning "without", is then attached. Thus, the literal construction "without a fathom" evolved logically into the modern abstract sense of an immeasurable or incomprehensible depth, whether physical, intellectual, or emotional.

Structure: fathom (measure depth) + less (without) - fathom: From Old English fæðm (outstretched arms, embrace, bosom, power), of Germanic origin. In this word, it functions as the core noun root meaning "a unit of measurement for depth". - less: From Old English -lēas (devoid of, free from), a suffix forming adjectives meaning "without".