The usual description of the process of back-formation is that a rule of
derivation is reversed (also called ‘reverse derivation’). In back-formation, a word is shortened into in a new part of speech is made from a longer, existing one, so that the effect is opposite of derivation. In English, a word-form ending in what appears like a noun suffix (such as ‘television’) or an adjective suffix (such as ‘crazy’) may undergo a process whereby the suffix-like element is deleted (‘television’ ‘televise’ and ‘crazy’ craze’) and the resulting forms (‘televise’ and ‘craze’) are used in different parts of speech—as a verb and a noun respectively. More examples in English include ‘lase’ (verb) from ‘laser’ (noun) and ‘edit’ (verb’) from ‘editor’ (noun).