Fathom — Defs

01 n. A measure of length, containing six feet; the space to which a man can extend his arms; -- used chiefly in measuring cables, cordage, and t…

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.[R.]
“Another of his fathom they have none To lead their business.” — Shak.

02 v. t. To encompass with the arms extended or encircling; to measure by throwing the arms about; to span.

imp. & p. p. Fathomed; p. pr. & vb. n. Fathoming

1.
To encompass with the arms extended or encircling; to measure by throwing the arms about; to span.[Obs.]
2.
To measure by a sounding line; especially, to sound the depth of; to penetrate, measure, and comprehend; to get to the bottom of.
“The page of life that was spread out before me seemed dull and commonplace, only because I had not fathomed its deeper import.” — Hawthotne.