after debating about Paraphrase in music and whether "paraphrasing" could mind something different I came to the question, that someone has been used the first time the German term of "leitmotif" which is used in French as well as in English language. Some one must have brought it up and someone must have adapted it.
Leitmotiv is a term, borrowed from the original German, that is often literally translated as "leading motive." More colloquially, it's a motive that serves to represent some aspect of a musical drama: it can be a location, an individual, an emotion, an item, etc.
It's most commonly associated with Wagner, and indeed it was popularized by Hans von Wolzogen when he made a guide to the Leitmotive of Wagner's Ring cycle. (Wagner, for what it's worth, hated the term and didn't use it.)
But von Wolzogen was not the first to use the term; the first printed use of the term was by Friedrich Wilhelm Jähns in a thematic guide to work by Carl Maria von Weber.
Discussions of Leitmotive these days are by no means limited to Wagner; they go back to von Weber (Der Freischütz especially) and earlier, and are also discussed in works by Berlioz, Richard Strauss, and others. It's become an especially important aspect of film music, especially in multi-film epics like The Lord of the Rings (which coincidentally shares source material with Wagner's Ring), Star Wars, and Harry Potter.