Plural in -en
The most common way of making a noun plural is by adding –en to the singular.
Likewise, you have to double the consonant after a short vowel sound:
Take care over the plural of nouns that end in –ee or or nouns that end in stressed –ie. The plural ending –en is still added, but it will be written as –ën to distinguish between the sounds (see Spelling and pronunciation). For example:
Plural in -s
If the singular ends in –e, –é, –el, –em, –en or –er, the plural is formed by adding –s to the singular. This is also often the case with words that are borrowed from foreign languages, e.g. mentor or telefoon.
If the singular ends in any other vowel than –e, the plural is formed with apostrophe + s (-‘s).
In a small number of cases the plural is formed by adding -eren to the singular.
Sometimes vowel changes occur when making the plural of nouns. Some short vowels become long in the plural and others change altogether, as you can see in a few common examples below:
Note that words that end in -heid, always have -heden in the plural.
When a new noun enters the language or is borrowed from another language, its plural may be formed in a different way.
Most words which are ‘borrowed’ from other languages actually end in a vowel or in -el, -em, -en or -er. In the plural, these nouns follow the normal rules for the formation of plurals.
Some words which have been taken from the English, keep their English plural -s.
A sign that words have been adapted fully, is that they receive a Dutch plural ending. An example is the word toilet (from the French) which has the plural toiletten.