The two dots above the letter “u” are known as a diaeresis or umlaut. They are used in some languages, including German and French, to indicate a specific pronunciation of the vowel. The diaeresis serves to separate the vowel from the letter “e” that follows it, indicating that the two should be pronounced as separate sounds.
In German, the diaeresis is often used with the letter “u” to indicate that it should be pronounced as a separate vowel sound rather than as part of a diphthong. For example, the word “fünf” (meaning “five”) contains a diaeresis over the letter “u” to indicate that it should be pronounced as a separate “oo” sound, rather than as part of the diphthong “eu”. Similarly, the word “Müller” contains a diaeresis over the letter “u” to indicate that it should be pronounced as a separate “u” sound, rather than as part of the diphthong “eu”.
In French, the diaeresis is also used to indicate a separate vowel sound. However, it is most commonly used with the letter “e” rather than the letter “u”. For example, the word “naïve” contains a diaeresis over the second letter “i” to indicate that it should be pronounced as a separate vowel sound, rather than being silent or forming a diphthong with the preceding “a”. Similarly, the word “Noël” contains a diaeresis over the letter “e” to indicate that it should be pronounced as a separate vowel sound, rather than being silent or forming a diphthong with the preceding “o”.
The use of the diaeresis in languages can be traced back to the ancient Greek language, where it was used to indicate a change in pronunciation of a vowel. The Greeks used the diaeresis to indicate that two adjacent vowels should be pronounced separately, rather than as a diphthong. This usage was later adopted by the Latin alphabet, and from there it spread to other languages.
In English, the diaeresis is rarely used today. It was once used in words such as “coöperate” to indicate that the two “o”s should be pronounced separately. However, this usage has largely fallen out of favor, and most English speakers today would write “cooperate” without the diaeresis.
In conclusion, the two dots above the letter “u” are known as a diaeresis or umlaut, and they are used in some languages to indicate a specific pronunciation of the vowel. The diaeresis serves to separate the vowel from the letter “e” that follows it, indicating that the two should be pronounced as separate sounds. While the diaeresis is still used in some languages today, its usage has largely declined in English over time.