-dır/-dir/-dur/-dür (ismi xəbər)

In Azerbaijani, the third-person singular assertive copula is used to form predicates from nominals (nouns, adjectives, etc.).

1. Vowel Harmony Rules:
The suffix changes its vowel to match the last vowel of the word it attaches to according to vowel harmony:

• -dır: After back unrounded vowels (a, ı). Example: almadır (it is an apple).
• -dir: After front unrounded vowels (e, ə, i). Example: müəllimdir (he/she is a teacher).
• -dur: After back rounded vowels (o, u). Example: dostdur (he/she is a friend).
• -dür: After front rounded vowels (ö, ü). Example: gündür (it is the day).

2. Pronunciation and Stress:
Crucially, this suffix is an enclitic, which means it never takes the word stress. The stress remains on the syllable immediately before the suffix. For example, in müəllimdir, the stress stays on the syllable -lim.

3. Consonant Stability:
The initial 'd' remains a 'd' even after voiceless consonants (like p, k, t, s). For example, 'It is a book' is kitabdır, not kitaptır.

4. Usage with Nominals vs. Verbs:
While often used with nouns and adjectives to sound more formal or assertive than the zero copula, this suffix is also frequently attached to verb forms like -mış, -acaq, or -malı in formal writing to indicate certainty (e.g., gəlmişdir - he has indeed come).

5. Plural Form:
To refer to multiple subjects, the plural suffix -lar/-lər is combined with the copula to form -dırlar/-dirlər. Example: Onlar tələbədirlər (They are students).