Fath″om (făt͡h″ŭm), n. [OE. fadme, faðme, AS. fæðm fathom, the embracing arms; akin to OS. faðmos the outstretched arms, D. vadem, vaam, fathom, OHG. fadom, fadum, G. faden fathom, thread, Icel. faðmr fathom, Sw. famn, Dan. favn; cf. Gr. ���������� to spread out, ������� outspread, flat, L. patere to lie open, extend. Cf. Patent, Petal.] 1. A measure of length, containing six feet; the space to which a man can extend his arms; — used chiefly in measuring cables, cordage, and the depth of navigable water by soundings.
2. The measure or extant of one's capacity; depth, as of intellect; profundity; reach; penetration.
Another of his fathom they have none
To lead their business. Shak.