The question concerns the definitions of the words in a poem. Here fray means to become unraveled because of constant rubbing. Of course, it is about the rope.
Tarnish means dullness or loss of color. The correct match is to become dull or spoiled after.
In informal meaning, bilge means rubbish and nonsense. However, the bilge itself is a ship's hull where the bottom of the ship meets the vertical sides and dirty water collects to that place.
Around 40% of words in the English language were borrowed or coined based on Latin roots or via French. Due to historical evolution of the Anglo Saxon society through time, from that large percentage, most words are used in scientific, legal, medical and academic terminology.
