In morphosyntax, a clitic is a bound element that is not as fully attached (to its host) as an affix is (to its base). The result of the combination of a clitic with its host is called clitic group.
Since Classical Greek and Latin only had enclitics, the term enclitic is older than the general term clitic. This general term was coined by back-formation only in the 20th century.
French clitique German Klitikon