(1) Old English phoulcat (foul cat). Originally a reference to the fitch, the wild ancestor of the domesticated ferret, because of their ability to emit a foul smelling spray when frightened. (2) Later, used in North America as a reference to the skunk. Both are actually not cats, but members of the weasel family, Mustelidae.
The symptoms of withdrawal can last for a few days up to a few weeks. It really is dependent on each person and their personal addiction. The most common withdrawal times usually last somewhere between a week and 14 days.
My drug of choice was opiates for almost 8 years and I relapsed over and over. The withdrawal time varied for me but I know once it took me a good month or two to feel better. Then, I would relapse most of the time. The first weeks are the worst and for some reason, when I would hit one week, I would feel the worst. Mostly psychologically.