Back in the day (waaaay back in the day) there was a tribe that centered itself around what is now Florida as well as the West Indies. This tribe was called the Arawakan. A subsection of this tribe that lived in Haiti was called the Taino people.
They used a word for fish nets that looked something like amaca. They also used this netting technology to sleep in which was an early form of what is know today as a hammock. When Spanish explorers met these people and saw their fish net style beds they interpreted the word a little differently than “amaca” and eventually turned it into “hamaca” and of course through time it became “hammock”.
For a deeper look into hammock history take a look at this article.