Island is a fun word. Even more fun is
isle. How often do you have a silent 's'? How did it come about?
Island appears to come from the Middle English
iland, from the Old English
igland. Dictionary.com says that the 's' comes from "association with
isle", and that
isle comes from the Latin
insula (meaning
island) through Old French. Merriam-webster.com confirms that
isle comes from "Anglo-French" and ultimately from Latin. The modern day word
insulate clearly comes from
insula, so that we can say that
insulate literally means "to make an
isle of (something)".
So
island comes from Old English, whereas
isle comes from Latin. We would be wrong, perhaps, to say that
insulate means "to make an
island of (something)" because
island doesn't come from
insula. Huh. I had assumed that
island and
isle had the same derivation and that
isle was simply a shortened form or something. Instead it appears that they have very different origins but that once they both made it into English their spellings converged.
A note: I had assumed that island and isle had identical meanings, but the two dictionary sites mentioned above both suggest that
isle often connotes a
small island. Thinking about it, perhaps this is right. Also, both sites claim that each word can be used as a verb (meaning, as you might expect, "to make into or place onto an
isle/
island").