German/Grammar/Noun plurals

Noun plurals
Forming the plurals of nouns is not quite as difficult as determining their gender, but it is comparable and the process is similar. There are rules you can learn to ease the load, but there are still plenty of exceptions which must be learned by rote.

While the gender of a noun is an intrinsic property of the noun, the number, singular vs. plural, is a function of what's going on in the sentence. So while you need to know the gender of a noun to successfully decline the words around it, the nouns themselves aren't declined by gender. The factors that do affect the way a noun is declined are case and number. We shall only cover the nominative case here; fortunately, declining nouns with respect to case is comparatively straightforward and will be done when we introduce the other cases.

Possible plural endings
Again, we shall only list rules which are either widely applicable or highly consistent. (See the previous section for the meanings of these terms.) The possible plural endings are -e, -(e)r, -(e)n and -(e)s. The optional -e- in the last three endings is included when it makes the plural easy to pronounce and left out otherwise. The actual rule is complicated because it depends on the last letter of the noun, and it's not always rigorously followed anyway, so it's better to just get a feel for it by example rather than to try to memorize all the specific cases. The fifth possibility is that there is no change to the ending at all. In addition, an umlaut might be added for the plural that's not in the original noun. This mostly happens with native German words, especially those with one syllable.

The most useful rules
Here are some of the most useful rules to find which of the five plural endings to use for a given noun.

Compounds
As with with gender, compound nouns follow the Right Hand Rules law for plurals well, in other words the plural of a compound follows the same pattern as the plural of the last part. Words with specific suffixes also tend to follow the same pattern for plurals, but in this case you can often get the same result by following the other rules given here.

Vowel endings
Nouns ending with -e almost always form plurals by adding -n, regardless of gender. This is a widely applicable and consistent rule.

Nouns ending with vowels other than -e, but including -y, almost always form plurals by adding -s. Most of them are imported from other languages and, as you might expect, those would form plurals with -s anyway, especially if the source language is English or French, but there are also words that are not imported in this category as well. For example: Exceptions:
 * Oma, Opa ("grandma", "grandpa") – Omas, Opas ("grandmas", "grandpas")
 * Firma ("firm, company") – Firmen ("firms")
 * Thema ("topic, theme") – Themen ("topics")
 * Ei ("egg") – Eier ("eggs")

Penultimate 'e'
Nouns ending in -en or -er, which account for most of the nouns whose next-to-last letter is 'e', usually form their plurals without an ending at all. One way to view this is that -en and -er are already plural endings, so it would be awkward to add another plural ending to them. Nouns ending in -el often follow this pattern as well, but there are so many exceptions to this that it shouldn't be relied on. Examples: Exceptions:
 * Kuchen ("cake") – Kuchen ("cakes")
 * Zimmer ("room") – Zimmer ("rooms")
 * Fehler ("error") – Fehler ("errors")
 * Words with the -chen diminutive suffix:
 * Mädchen ("girl") – Mädchen ("girls")
 * Nouns formed from verbs:
 * Essen ("food") – Essen ("foods") – from essen ("to eat")
 * Words with the -er suffix denoting function, job, or origin:
 * Fahrer ("driver") – Fahrer ("drivers")
 * Relatives; these usually have an umlaut in the plural:
 * Bruder ("brother") – Brüder ("brothers")
 * Schwester ("sister") – Schwestern ("sisters")
 * Nummer ("number") – Nummern ("numbers")

Foreign nouns
Imported words tend to declined as in the language of origin, so, as mentioned above, nouns borrowed from French and/or English usually use the -(e)s ending in plurals. In addition to the examples already listed, there are:
 * E-Mail ("e-mail") – E-Mails ("e-mails")
 * Hotel ("Hotel") – Hotels ("Hotels")
 * Restaurant ("Restaurant") – Restaurants ("Restaurants")

Masculine nouns
When none of the above rules are applicable then you can usually find the plural using gender alone. These rules tend to have many exceptions though. Masculine nouns tend to use the -e ending to form plurals. For example:
 * Tisch ("table") – Tische ("tables")
 * Schuh ("shoe") – Schuhe ("shoes")
 * Hund ("dog") – Hunde ("dogs")

There is, however, a subset of masculine nouns that use the -(e)n ending. These are troublesome since, as we'll be covering later, they make declining nouns with respect to case much more difficult. These include: Many, but not all, of these nouns end with -e, so these follow the -e ending rule mentioned earlier.
 * Junge ("boy") – Jungen ("boys")
 * Name ("name") – Namen ("names")

There are, of course, masculine nouns that don't seem to fit into any pattern:
 * Mund ("mouth") – Münder ("mouths")

Feminine nouns
Feminine nouns almost always use the -(e)n to from plurals: Many of these nouns end with -e so this is consistent with the -e ending rule given above.
 * Ecke ("corner") – Ecken ("corners")
 * Kartoffel ("potato") – Kartoffeln ("potatoes")
 * Katze ("cat") – Katzen ("cats")

Although the rule for feminine plurals is relatively consistent, there are always a few oddballs:
 * Hand ("hand") – Hände ("hands")
 * Stadt ("city") – Städte ("cities")

Neuter nouns
Common wisdom says that neuter nouns tend to use the -(e)r ending. There are, however, nearly as many that use the -e ending, so unless you are allowed two guesses this rule is not as useful as you might hope. Examples with -(e)r:
 * Ei ("egg") – Eier ("eggs")
 * Kind ("child") – Kinder ("children")
 * Lied ("song") – Lieder ("songs")

Examples with -e:
 * Brot ("loaf of bread") – Brote ("loaves of bread")
 * Haar ("a single hair") – Haare ("hairs", including the hair on someone's head)

A neuter noun that does not follow either pattern is: It does end with an -e though, so the corresponding rule applies in this case.
 * Auge ("eye") – Augen ("eyes")

Umlauts
As seen in some of the examples above, some nouns add an umlaut to their plurals as well as, or instead of, changing their ending. As mentioned above, this happens most frequently with single syllable words and sometimes with two syllable words, generally those that have been in the language for a long time. Some examples not already mentioned:
 * Fuß ("foot") – Füße ("feet")
 * Dorf ("village") – Dörfer ("villages")
 * Garten ("garden") – Gärten ("gardens")

Singular only and plural only nouns
As in English, German has some nouns that either have no plural at all, or if they do then they are only used in certain circumstances. Similarly German has its share of nouns with no singular form. (Grammarians call these, if you want to really delve into the jargon, singularia tantum and pluralia tantum.) The situation in German is a bit more subtle than it is for English, and we'll have more to say on this when we introduce articles in the next section. Singular only nouns are usually:
 * Substances, for example:
 * Wasser – ("water")
 * These generally can form plurals if you're talking about different types and certain other cases.
 * Abstract concepts, for example:
 * Hunger – ("hunger")
 * Something that only exists as a single entity:
 * Internet – ("internet")

Plural only nouns are more difficult to classify. Examples are Note that the English versions of these words do have singular forms (though "person" as the singular of "people" is arguable), but English has its own examples such as "pants" and "scissors" for which the German equivalents are singular, Hose and Schere.
 * Eltern – ("parents")
 * Leute – ("people")

Summary
These rules allow you to find the plurals of nouns more often and more reliably than the rules for finding their gender given in the previous section. This is an unfair comparison though since many of them assume that you already know the gender of the noun in question; without knowing the gender these rules would be similarly incomplete and unreliable. Fortunately, once you have the gender and plural of a noun, you can easily fill in its entire declension table in the vast majority of cases. We're leaving out here a small but significant class of nouns derived from adjectives, and they decline more like their adjective parents than actual nouns. We'll say more about them later but we'll need to do adjectives first.