Plurals

The plural suffixes are –ler and –lar. All the nouns, countable or uncountable, and all the adjectives can be made plural. Adjectives function as a noun in this case.

When adding a plural suffix to a word you normally have to choose the vowel that harmonizes with the last vowel in the receiving word. If the last vowel of the receiving word is one of the high vowels (e – i – ö – ü ) add –ler suffix to the word.

Examples:

defter (notebook) defterler
öğrenci (student) öğrenciler
şeker (sugar) şekerler
göl (lake) göller
ev (house) evler
gün (day) günler
İngiliz (Englishman) İngilizler
güzel (beautiful) güzeller
pencere (window) pencereler
ekmek (bread) ekmekler

If the last vowel of the receiving word is one of the low vowels ( a – ı – o – u ) add –lar suffix to the word.

Examples:

okul (school) okullar
masa (table) masalar
bardak (glass) bardaklar
kalın (thick) kalınlar
kız (girl) kızlar
ulus (nation) uluslar
telefon (phone) telefonlar
bekar (single) bekarlar
su (water) sular
çay (tea) çaylar
kırmızı (red) kırmızılar

If the last consanant of a word is “l” with a preceding vowel double the letter “l” when adding plural suffixes –ler or –lar as in examples below:

dal (branch) dallar
el (hand) eller
kıl (hair) kıllar
dul (widow) dullar
kel (bald) keller
göl (lake) göller
çöl (desert) çöller
dil (tongue, language) diller
mal (property) mallar

The use of plurals
The plural suffix is added to indicate plurality. If plurality is shown by a numeral greater than one or a word like “çok” (many), or “kaç” (how many), no plural suffix is added to the noun as in examples below:

iki kitap (two books) not ”iki kitaplar”
çok bardak (a lot of glasses) not “çok bardaklar”
kaç kişi (how many people) not “kaç kişiler”

Sınıfta on beş öğrenci var. There are fifteen students in the class.
Dolapta çok bardak var. There are a lot of glasses in the cupboard.
Partide kaç kişi vardi. How many people were there in the party?
Kalemler çekmecede. The pencils are in the drawer.


In question and negative “…var mı?” (Is / are there any…) and “…yok” (There isn’t / aren’t any…) sentences plural suffix is not added to the noun as in examples below:

Sınıfta hiç öğrenci var mı? Are there any students in the class?
Masada hiç kitap yok. There aren’t any books on the table.
Buzdolabında hiç yumurta yok. There aren’t any eggs in the fridge.

Some Exceptions:
There are a very few exceptions to this rule where the suffix does not echo Vowel Harmony exactly - as examples:

saat (hour, clock) saatler not saatlar
harf (letter (of alphabet)) harfler not harflar
vaat (promise) vaatler not vaatlar
kalp (heart) kalpler not kalplar
gol (goal) goller not gollar
sembol (symbol) semboller not sembollar
misal (example) misaller not misallar

These words are not Turkish words originally. That is why they don't echo vowel harmony rules when suffixes are attached to them.