Contents introduction chapter I historical background of etymological doublets

Native origin
Most simply, a native word can at some point split into two distinct forms, staying within a single language, as with English too which split from to. Alternatively, a word may be inherited from a parent language, and a cognate borrowed from a separate sister language. In other words, one route was direct inheritance, while the other route was inheritance followed by borrowing. In English this means one word inherited from a Germanic source, with, e.g., a Latinate cognate term borrowed from Latin or a Romance language. In English this is most common with words which can be traced back to Indo-European languages, which in many cases share the same proto-Indo-European root, such as Romance beef and Germanic cow.
However, in some cases the branching is more recent, dating only to proto-Germanic, not to PIE; many words of Germanic origin occur in French and other Latinate languages, and hence in some cases were both inherited by English (from proto-Germanic) and borrowed from French or another source – see List of English Latinates of Germanic origin. The forward linguistic path also reflects cultural and historical transactions; often the name of an animal comes from Germanic while the name of its cooked meat comes from Romance. Since English is unusual in that it borrowed heavily from two distinct branches of the same language family tree – Germanic and Latinate/Romance – it has a relatively high number of this latter type of etymological twin. See list of Germanic and Latinate equivalents in English for further examples and discussion.²
Less commonly, a native word may be borrowed into a foreign language, then reborrowed back into the original language, existing alongside the original term. An English example is animation and anime "Japanese animation", which was reborrowed from Japanese アニメ anime. Such a word is sometimes called a Rückwanderer (German for "one who wanders back").
In case of twins of foreign origin, which consist of two borrowings (of related terms), one can distinguish if the borrowing is of a term and a descendant, or of two cognate terms (siblings). Etymological twins are often a result of chronologically separate borrowing from a source language. In the case of English, this usually means once from French during the Norman invasion, and again later, after the word had evolved separately in French. An example of this is warranty and guarantee. Another possibility is borrowing from both a language and its daughter language. In English this is usually Latin and some other Romance language, particularly French – see Latin influence in English. The distinction between this and the previous is whether the source language has changed to a different language or not³.
Less directly, a term may be borrowed both directly from a source language and indirectly via an intermediate language. In English this is most common in borrowings from Latin, and borrowings from French that are themselves from Latin; less commonly from Greek directly and through Latin. In case of borrowing cognate terms, rather than descendants, most simply an existing doublet can be borrowed: two contemporary twin terms can be borrowed. More remotely, cognate terms from different languages can be borrowed, such as sauce (Old French) and salsa (Spanish), both ultimately from Latin, or tea (Dutch thee) and chai (Hindi), both ultimately from Chinese. This last pair reflects the history of how tea has entered English via different trade routes.
Sometimes a word is borrowed twice from the same language. As the result, we have two different words with different spellings and meanings but historically they come back to one and the same word. Such words are called etymological doublets. In other words, two or more words in the same language are called doublets or etymological twins (or possibly triplets, etc.) when they have the same etymological root but have entered the language through different ways. They differ to a certain degree in form, meaning and current usage. Etymological twins are usually a result of chronologically separate borrowing from a source language. In the case of English, this usually means once from French during the Norman invasion, and again later, after the word had evolved. e.g. warranty (гарантия) and guarantee.
There are also etymological doublets which were borrowed from the same language during different historical periods, such as French doublets: gentil - любезный, благородный, etymological doublets are: gentle - мягкий, вежливый and genteel - благородный. From the French word gallant etymological doublets are : ‘gallant - храбрый and ga’llant - галантный, внимательный. Sometimes etymological doublets are the result of borrowing different grammatical forms of the same word, e.g. the Comparative degree of Latin «super» was «superior» which was borrowed into English with the meaning «high in some quality or rank». The Superlative degree (Latin «supremus») in English «supreme» with the meaning «outstanding», «prominent». So «superior» and «supreme» are etymological doublets.

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