Loanwords are words that are borrowed from another language at some point in the language's history, but that have usually adapted to the phonetic system of the new language. They are not always recognizable as such by laymen without an etymological analysis of the word.
Loanwords point to historical contact between two languages (there must have been speakers with sufficient knowledge of both languages at some stage). Italian musical terms, for example, enter the English language from the late 17th century and the 18th. Loanwords have to be distinguished from inherited words, which refer to a genealogical relatedness (i.e. words inherited from a common ancestral language).
Loanwords may keep the same meaning in the receiving language, but they may also acquire a different or broader meaning. Recent borrowings that have kept exactly the same meaning along with the same orthography, such as espresso, carpaccio, etc., are not included in our list. Their origin is obvious and their etymological and historical interest, therefore, is rather limited.
We also differentiate loanwords from calques, a calque being a complex form created on the model in a donor language and whose constituents correspond semantically to the donor language constituents (e.g. French lune de miel calqued from English honeymoon). The word 'loanword' itself is also a calque from the German Lehnwort. From an etymological point of view, calques are closer to neologisms than to loanwords.
The interest of studying loanwords resides in the fact that it can tell us a lot about the type of contact situation between two populations. A language of a population conquered by war may be likely to borrow military terms from the conquerors' language.
The Italian language has contributed many musical, medical, banking, culinary and other terms in English and the other European languages. Our list of italian loanwords includes words borrowed from Italian, either directly into English or borrowed from Italian into English through other languages, such as (Old, Middle or Modern) French. See our list of Italian loanwords in English.
Bibliography: Chambers Dictionary of Etymology, Robert K. Barnhart (Ed.), the H.W. Wilson Company
La Lingua Italiana by Maurizio Dardano and Pietro Trifone
Dictionary of Languages by Andrew Dably
The Languages of the World by Kenneth Katzner
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