A course In Modern English Lexicology

§ 9. Degree of Assimilation
words in the English word-stock shows that
and Factors Determining It
there are words among them that are easily
recognised as foreign (such as decolleté, façade, Zeitgeist, voile) and there are others that have become so firmly rooted in the language, so thoroughly assimilated that it is sometimes” extremely difficult to distinguish them from words of Anglo-Saxon origin (these are words like pupil, master, city, river, etc.).
Unassimilated words differ from assimilated ones in their pronunciation, spelling, semantic structure, frequency and sphere of application.
However, there is no distinct border-line between the two groups. There are also words assimilated in some respects and unassimilated in others, they may be called partially assimilated. Such are communiqué, détente not yet assimilated phonetically, phenomenon (pl. phenomena), graffito (pl. graffiti) unassimilated grammatically, etc. So far no linguist has been able to suggest more or less comprehensive criteria for determining the degree of assimilation of borrowings.
The degree of assimilation depends in the first place upon the time of borrowing. The general principle is: the older the borrowing, the more thoroughly it tends to follow normal English habits of accentuation, pronunciation, etc. It is natural that the bulk of early borrowings have acquired full English citizenship and that most English speaking people are astonished on first hearing, that such everyday words as window, chair, dish, box have not always belonged to their language. Late borrowings often retain their foreign peculiarities.
However mere age is not the sole factor. Not only borrowings long in use, but also those of recent date may be completely made over to conform to English patterns if they are widely and popularly employed. Words that are rarely used in everyday speech, that are known to a small group of people retain their foreign -peculiarities. Thus many 19th century French borrowings have been completely assimilated (e.g. turbine, clinic, exploitation, diplomat), whereas the words adopted much earlier noblesse
[no'bles] (ME.), ennui [ã:'nwi:] (1667), eclat [ei'kla:] (1674) have not been assimilated even in point of pronunciation.
Another factor determining the process of assimilation is the way in which the borrowing was taken over into the language. Words borrowed orally are assimilated more readily, they undergo greater changes, whereas with words adopted through writing the process of assimilation is longer and more laborious.
1. Due to “the specific historical development