The word exception is loaded. The definition seems clear: exceptions are exceptional. I'll say, in Python at least, this definition is simply not true. A normal Python program may handle and raise any number of exceptions as it hums along quite nicely.

Consider the Pythonic idiom we have already pointed out multiple times: Easier to Ask Forgiveness than Permission. It is usually expressed as follows:

try:
    spam.eggs()
except AttributeError:
    spam.ham()

The preceding code is preferred over the following code, which uses a Look Before You Leap style:

if hasattr(spam, 'eggs'):
    spam.eggs()
else:
    spam.ham()

There is nothing exceptional about exceptions in the first example. Describing them as exceptional is more accurate when describing how they behave rather than how they are used.

I prefer the following definition:

To illustrate that definition, consider the following lines of code:

if spam:
    for i in xrange...