Amyl Alcohol can actually refer to any one of the eight different alcohols with the formula C5H11OH. Amyl Alcohol is most often obtained from using fusel alcohols, which is usually the byproduct of alcohol fermentation.
If just the phrase Amyl Alcohol is used, then it is to be assumed that it is in reference to the normal form, 1-pentanol. Any other types of Amyl Alcohol should be specified further to help inform which one is being referred to.
Some of the different types of Amyl Alcohol can be obtained synthetically through production in the lab, but others can be found in their natural state.