For more than a decade or two, contemporary American English speakers have gotten into the habit of substituting the bookish adjective multiple for the simple count adjective many, as in the followings usages (adapted from the Merriam-Webster Unabridged Dictionary online):
1. ‘many, manifold, several’ <multiple achievements in politics and public life––<multiple minds functioning together>––<multiple copies of a speech>
2. ‘occurring more than once or in higher degree than the first; repeated’ <multiple roots>
In all of the cited examples, the more direct way of denoting ‘more than few’ would be with the word many. Why, then, is there a trend in recent years to replace it with multiple?
The answer may be the principle of ICONICITY AS THE TELOS OF LINGUISTIC CHANGE. The word many has only two syllables, whereas multiple, while seeming orthographically to have two as well, is actually pronounced with a schwa vowel between the consonants at the end of the word, making it tri- and not disyllabic. A trisyllabic word is more adequate iconically to the meaning of multiplicity than is a disyllabic one. QED.