?
I believe that was what the indigenous inhabitants told Columbus it was called in their Arawak language.
Friday Harbor in Washington State was named as such when ogical surveyor came out to the bay to name it. When he got there he saw a man on the shore and yelled out to him “What bay is this?”. The man replied “Friday.” He had thought he asked what day it was. 
True story.
Because “England” and “France” were already taken. 
Because “Unnamed Landmass Libre” is a stupid name for a drink.
Cuba comes from the Arabic word for ‘dome’, qubbah. (The Dome of the Rock in Arabic is Qubbat al-Sakhrah.) Columbus reported in his journal that when sailing the coast of Cuba they sighted “a mosque” (una mezquita) on top of a hill. It was some dome-shaped structure, whether natural or man-made is not known, and its domed shape reminded Columbus of a mosque. The English word alcove comes from the same source, Arabic al-qubbah via Spanish; originally meaning ‘a domed vault’. Spanish doesn’t use doubled consonants (except for rr), so they reduced the Arabic double bb to a single b in Cuba.
Jomo, I’m always very impressed by your knowledge of linguistics but I’m going to have to ask for more of a back-up on this one. Every site I checked traced the derivation to “cubanacan,” a Taino (Arawak) word meaning “a central place.” This derivation seems more inherently plausible than the one you suggest.
This site gives quotes from Columbus’s journal translated into English. He apparently first hears the big island referred to as “Cuba” on October 26, 1492; arrives at the island on October 28th; and sees a hill shaped “like a mosque” on the 29th. Unfortunately, I haven’t been able to find the original text in Spanish on-line. However, if your hypothesis is correct, I am wondering how, in the Spanish text, Columbus referred to “Cuba” text before he actually saw the mosque-like hill.
Sorry, Colubus first heard of Cuba on October 21, not the 26th, more than a week before his sighting of the mosque-like hill.
All right, you got me there, Colibri. It’s Taino after all.
One other point: Las Casas, in History of the Indies, alleges that the word “cubanacan” helped reinforce Columbus’s conviction that he was in the (East) Indies. Las Casas says that Columbus misheard it as El Gran Can (the Great Khan), making him think he was nearing the court of the Chinese Emperor.