Summary: Prefixes often undergo spelling changes depending upon the stem, or main part of the word, to which they are affixed. The prefix *con-*, for example, can exist in the following forms: *co-*, *col-*, *com-*, and *cor-*. Examples of words containing such forms include [*co*]operate, [*col*]laborate, [*com*]panion, and [*cor*]rect.
