I'm not so certain that the issue is the definition of the term normal, so much as it is the value (positive or negative) or association (healthy vs. unhealthy) the term implies in a medical or social context.
One of the most common reasons for blurry vision while wearing contacts is that your eyes are dry. Some people have a medical condition that causes dry eyes, called dry eye syndrome, but others' eyes are irritated by the contacts themselves.
Cloudy vision, where objects are obscured and appear milky, is often mistaken for blurry vision. Cloudy vision usually is a symptom of specific conditions such as cataracts, but blurry and cloudy vision can both be symptoms of a serious eye problem.