fathom

fathom verb [ T ] uk/ˈfæðəm/ us( also UK fathom out)
to be able to understand something after thinking about it a lot

понимать, постигать
[ + question word ] No one could fathom why she had left so early.

FATHOM noun

[ C ] uk/ˈfæðəm/ us
a unit for measuring the depth of water, equal to 1.8 metres

морская сажень