fathom
noun.
a linear unit of measurement (equal to 6 feet) for water depth
Synonym: fthm
noun.
(mining) a unit of volume (equal to 6 cubic feet) used in measuring bodies of ore
Synonym: fthm
verb.
come to understand
Synonym: bottom, penetrate
verb.
measure the depth of (a body of water) with a sounding line
Synonym: sound