Categorical or Categorial? Is there a difference between the two terms from a statistician's point of view? I have heard about Categorical distribution and Categorical variables in statistics. But what is a Categorial variable? Can both Categorial and Categorical be used interchangeably? Are there specific cases in which we use either of these terms?

I second mkt's answer; this is a long comment rather than an answer. In math I've never seen "Categorial".
Also, I think in English that word is rarely used. The frequency is about 20 times less than the proper word "categorical"

I asked a question here and English experts will surely help us.
