"I remember reading somewhere that the term "angler" comes from the fact that the fish-hook used to be called the "angle", so someone who uses an angle is an angler. Now you'll have to ask where the origin of the word "angle" is!"
setomonkey has got it right. Back when the term was coined rudimentary fishing hooks were bent at a 45 degree angle and resembled the leter "V" thus, fish hooks were known as angles and fishermen as anglers. And on a somewhat unrelated note the term "splitshot", which was coined around the same time, was derived from the action of navle offisers using a knife to cut a notch in lead musket round inorder to use it to weight their lines.
