Key Takeaways
A tiny mark, the two dots (¨), can carry big meaning. In Dutch, this symbol is called the trema and signals that two adjacent vowels are pronounced in separate syllables rather than merged. In Spanish, the equivalent name is diéresis, used only over ü to mark a special pronunciation. In English, the term diaeresis (or dieresis) covers similar uses: two dots over a vowel to indicate that it doesn’t form part of a digraph or diphthong.
Dutch uses the trema most often on ë and ï, occasionally on ö, and virtually never on ä in native words. In French, the diacritic mark is called tréma, derived from Greek trêma (“hole”), which shows the evolution of names in different languages.
When learning Dutch spelling, knowing when the trema is required helps avoid mis-reading: the trema is mandatory if omission would lead to wrong syllabification. It doesn’t change the vowel’s sound (unlike German’s umlaut) — it clarifies syllable division.
Story & Details
Imagine writing the sentence in Dutch: Ik kom uit Argentinië, maar ik woon in Mexico. The word Argentinië features ë with the two dots. That trema tells you that “ie-ë” are not fused into one sound but should be read as three: ni-ë. It ensures the correct syllable separation.
You might ask: is the trema always needed? Why don’t you see ä in Dutch? What about ö? The answer: Dutch orthography dictates the trema whenever two vowels risk merging into one sound yet are meant to be pronounced separately. It’s mandatory in those cases because it affects how the word is read. The letter ä rarely appears in standard Dutch; it’s mainly found in loan-words from German or other languages. The ö, however, will show up in some borrowed or technical words (like coördinatie, where ö marks separation of “o” and “o” rather than a sound change).
When you ask how to call the two-dot mark in Dutch, you learn that “trema” is the everyday term, while “deelteken” is the formal grammatical term meaning “division mark” or “separation sign”. Example sentences in Dutch:
- Het woord zeeën heeft een trema. (“The word zeeën has a trema.”)
- In het woord coördinatie staat een deelteken. (“In the word coördinatie there is a trema.”)
The etymology of these terms sheds further light. The English term diaeresis comes from Greek diaíresis meaning “division” or “separation”. The French term tréma comes from Greek trêma, meaning “hole” or “perforation”, and refers to the mark itself more than the process. That explains why French uses diérèse (for the process of separation) and tréma (for the two-dot mark) separately.
Here is a video that explains the use of the two-dots mark in Dutch:
What is the double dot ¨ on letters in Dutch?
Definitions & Translations
Trema – the two-dot diacritic mark (¨) used in Dutch to show that adjacent vowels belong to separate syllables, not a diphthong. Derived from Greek trêma.
Deelteken – the Dutch grammatical term meaning “dividing sign” used in formal discussion of the trema.
Diéresis – the Spanish term for the same symbol (¨) but used in Spanish orthography only over the letter ü to signal pronunciation in güe/güi.
Diaeresis (also spelled dieresis) – the English name for the two-dot diacritic when used to separate vowels into distinct syllables (e.g., naïve, coöperate).
ë / ï in Dutch – the vowels on which the trema most frequently appears in everyday Dutch (for example: zeeën, Ruïne).
ö in Dutch – appears occasionally in borrowed or technical Dutch words; the trema ensures that the “o-o” sequence is not read as one sound.
ä in Dutch context – essentially absent in standard Dutch spelling; mostly found in loan-words from German or Scandinavia.
Conclusions
In the world of spelling, those two little dots matter more than you might expect. In Dutch, the trema is a marker of clarity — it guarantees that each vowel is heard and counted as its own syllable when needed. For learners of Dutch, the rule is simple: when you find two vowels together and you’re unsure whether they form a single sound or separate ones — look for the trema. Focus first on ë and ï, since they occur most often. Understand that ö appears mainly in special cases, and you need not worry about ä in everyday Dutch. The trema does not alter the vowel’s quality (unlike the German umlaut) — rather, it partitions sounds and guides reading. Once that becomes second nature, you’ll recognise words like Argentinië, zeeën, ideeën, or coördineren with confidence. Those two dots may seem small, but they guide syllables and pronunciation with precision.
Sources
- What is the double dot ¨ on letters in Dutch? YouTube. https://www.youtube.com/watch?v=OjxXqCim624
- Diaeresis (diacritic) – Wikipedia. https://en.wikipedia.org/wiki/Diaeresis_%28diacritic%29
- Two dots (diacritic) – Wikipedia. https://en.wikipedia.org/wiki/Two_dots_%28diacritic%29
- Dutch orthography – Wikipedia. https://en.wikipedia.org/wiki/Dutch_orthography
- Ë (Wikipedia entry on letter usage). https://en.wikipedia.org/wiki/%C3%8B
Appendix
Example words:
- zeeën → zee (sea) + ën (plural) — trema on ë separates syllables: zee-ën.
- coördinatie → co-ö-r-di-na-tie — the trema on ö makes sure “o” + “o” are pronounced separately.
- Argentinië → Ar-gen-ti-ni-ë — the trema on ë signals the sequence “ie-ë” does not merge.
My Diary - Leonardo Cardillo 