Words adopted by a language undergo assimilation in different degree. Some of the words are unassimilated, or barbarisms. They are easily recognized as foreign, e.g. Zeitgeist (<Germ.), façade (<Fr.).
Completely assimilated words follow all morphological, phonetic and orthographic standards of Modern English language. They are mostly found in older layers of borrowings: early Latin cheese, street, dish, wall, etc.; Scandinavian husband, window, fellow, gate, root, etc.; French table, chair, pencil, face, figure, etc.; late Latin animal, article, etc.
Partially assimilated are subdivided into subgroups:
1. Loan words not assimilated semantically because they denote objects and notions peculiar to the country which they come from: foreign clothing, titles, professions, food and drinks: kimono, sari, sombrero, rajah, sheik, toreador, ricksha(w),koumiss, pizza, shish-kebab, etc.
2. Loan words not assimilated grammatically: nouns borrowed from Latin and Greek as Gk phenomenon (pl. -a), L. crisis (pl.- es), etc.
3. Loan words not completely assimilated phonetically. Here belong French borrowings with the accent on the last syllable: machine, police, cartoon, etc. Others contain sounds that do not occur in native words: [ğ] bourgeois, prestige, [wa:] memoir, nasalized [ã], [õ],[ ĩ], timbre, melange, etc.
4. Loan words not completely assimilated graphically. Here belong words borrowed from French in which final consonants are not pronounced: ballet [`bælei], buffet [`bufei], corps [ko:]; words of Greek origin with the initial ?p? not pronounced: psychology, pneumonia, pneumatics. Some French loans keep a diacritic mark: café, cliché, the letter ç: façade. Specifically French digraphs: (ch [ş], qu, ou [u:])are retained in many words, e.g. bouquet, rouge, chic.
One and the same word often shows incomplete assimilation in several respects simultaneously, e.g. bouquet [bu`kei] not completely assimilated phonetically and graphically.
The degree of assimilation depends in the first place upon the time of borrowing. The general tendency is that the older the borrowing, the more thoroughly it tends to follow English standards of spelling, pronunciation, etc. It is natural that early loans like dish, cup, window, chair became part and parcel of English lexicon. Late borrowings often retain their foreign peculiarities. However, the time of borrowing is not the sole factor. Borrowings of recent date may be completely assimilated, e.g. Late French borrowings: pilot, apartment, detail.
The next important factor is frequency of usage. Words that are rarely used in everyday speech, that are known to a small group of people, retain their foreign peculiarities. 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 than those adopted via written documents. For example, words borrowed in 18-20 c. pilot, detail orally are assimilated in greater degree than memorandum, communiqué.