The aim of this book is to provide a linguistic description of borrowings in informal American English and to serve as a practical resource documenting this type of language. These foreign-origin expressions, comprising both slang and colloquialism, constitute a vibrant sociolinguistic phenomenon resulting from language contact, and function as an important yet rarely discussed lexical contribution to American English. Their significance stems from the sociolinguistic significance of informal language in the United States, the strong presence of borrowings in American speech reflecting the immigrant nature of the country and the growing role of ethnic minorities, as well as the increasingly common use of this type of lexicon among larger segments of American society.