fathom
n//ˈfað(ə)m//famn, begripa, famna om, fatta, förstå, omfamna, loda
(chiefly, nautical, historical, US) A man's armspan, generally reckoned to be six feet (about 1.8 metres). Later used to measure the depth of water, but now generally replaced by the metre outside American usage.
(archaic, or, obsolete) To encircle (someone or something) with outstretched arms; specifically, to measure the circumference or (rare) length of something.
(figurative) Often followed by out: to deeply understand (someone or something); to get to the bottom of.
(also, figurative) To measure the depth of (water); to take a sounding of; to sound.