wrote the o and e separately, but the ligature was used by medieval and early modern writings, in part because the diphthongal sound had, by Late Latin, merged into the sound. The classical diphthong had the value, similar to English oy as in boy. It occurs most often in borrowings from Greek, rendering that language's οι, although it is also used in some native words such as coepi.
French
In French, œ is called e dans l'o, which means e in the o or sometimes o et e collés, and is a true linguistic ligature, not just a typographic one, reflecting etymology. It is most prominent in the words , Kœtzingue, and Hœrdt. In all cases, œ is alphabetized as oe, rather than as a separate letter. When oe occurs in French without the ligature, it is pronounced, just like words spelt with oi. The most common words of this type are needs to be added in order to indicate that the vowels should be pronounced separately. For example, wikt:Noël, wikt:poésie, wikt:poète. The exception to this rule is when a morpheme ending in o is joined to one beginning in e, as in wikt:électroencéphalogramme, or with the prefix co-, which is always pronounced in hiatus with the following vowel, as in wikt:coefficient.
English
A number of words written with œ were borrowed from French and from Latin into English, where the œ is now rarely written. Modern American English spelling usually substitutes e, so diarrhœa has become diarrhea, although there are some exceptions, such as phoenix. In modern British English, the spellings generally keep the o but remove the ligature. The œ ~ oe ~ e is traditionally pronounced as "short E", as "long E", or as an unstressed vowel. These three Modern-English values interchange with one another in consistent ways, just as do the values within each of the sets from the other vowel-spellings that at the Middle English stage likewise represented non-diphthongs—except for, as was recognised particularly in certain positions by Dobson, a tendency whereby "... long vowels are, in later use, often substituted... cf. Pres E 'economic' in place of the popular , which is in accord with the normal rules and must be regarded as the traditional and naturally-developed pronunciation...". There are a few words that English has recently borrowed from contemporary French. The pronunciation of these English words is generally an approximation to that of the French word. English-speakers use a variety of substitutions for these sounds. The words involved include. These recent borrowings from French include manœuvre, hors d'œuvre, œuvre, and œil de bœuf However most œ words use the traditional English pronunciation of borrowings from/via pre-modern French and from/via Latin, and examples are listed in the following categories, into which they have been divided by developments in our pronunciation since Middle English.
An overriding rule is that where œ ~ oe ~ e is followed by another vowel of stress we pronounce it as "long E".
In :wikt:open syllable|open syllables immediately following or preceding a syllable that bears primary or secondary stress, we pronounce an œ ~ oe ~ e as an unstressed vowel, that is, as the unstressed one that sounds like "short I" or instead of it for some dialects as shwa.
We also use long E for œ ~ oe ~ e in a primary-stressed open syllable that lies within the final two syllables of the word if the final syllable begins with a vowel while the penultimate ends in a vowel other than o or u.
Finally, there are some cases where we use a "short E", as what Dobson called in the quote above the "naturally-developed pronunciation" though "the long vowels are, in later use, often substituted":
for an œ ~ oe ~ elying in a secondarily-stressed syllable not adjacent to the primary-stressed one, as in fœderation, œcologic, œconomic, œcumenic and œstrogenic;
for an œ ~ oe ~ e in a closed syllable anywhere as long as it bears some stress, as in œstrogenic; œstrogen; and œstrus;
for an œ ~ oe ~ e in a primary-stressed syllable that does not lie within the final two of the word.
Œ is used in the modern scholarly orthography of Old West Norse, representing the long vowel, contrasting with ø, which represents the short vowel. Sometimes, the ǿ is used instead for Old West Norse, maintaining consistency with the designation of the length of the other vowels, e.g.mǿðr "mothers". Œ is also used to express, regardless of the length of the vowel, in the modern scholarly orthography of Middle High German. Œ is not used in modern German. Loanwords using œ are generally rendered ö, e.g. German, especially in the names of people and places. Like German, Danish does not use œ, but unlike German, Danish replaces œ or œu in loan words with ø, as in wikt:økonomi "economy" from Greek via Latin wikt:œconomia or wikt:bøf "beef" from French wikt:bœuf''.
In Unicode, the characters are encoded at and. In ISO-8859-15, Œ is 0xBC and œ 0xBD. In Windows-1252, at positions 0x8C and 0x9C. In Mac-Roman, they are at positions 0xCE and 0xCF. Œ and œ were omitted from ISO-8859-1, which are still widespread in internet protocols and applications. Œ is the only character in modern French that is not included in ISO-8859-1, and this has led to it becoming replaced by 'oe' in many computer-assisted publications. This was due, in part, to the lack of available characters in the French ISO/IEC 646 version that was used earlier for computing. Another reason is that œ is absent from most French keyboards, and as a result, few people know how to input it. The above-mentioned small capital of the International Phonetic Alphabet is encoded at.
