fathom

As a unit of measurement, a fathom is six feet.
 * ~Define this word.**

15 fathoms = 90 feet 40 fathoms = 240 feet It also means, "to understand". How for long hours have I pondered upon it! How have I, through the whole of a midsummer night, struggled to fathom it!
 * ~Give the sentence in which it appears in the story.**
 * ~Illustrate this word with an image/video.**

{Could not find one @_@]