what is it?
The suffix -DIr is a non-past copular ending that serves two related functions. First, in spoken and written language it signals assumption or probability: the speaker infers or supposes something rather than reporting a directly witnessed fact. Second, in formal written registers it marks neutral generalization or definition, the kind found in encyclopaedias, official documents, academic prose, and news writing. In everyday casual speech the bare predicate (without any suffix) is the default for plain known facts, so -DIr carries a noticeable weight whenever it appears.
when to use it
Assumption / probability (spoken or written). Use -DIr when you are inferring a present-state fact rather than observing it directly. The meaning is roughly «probably» or «I expect that…». Example: O şu an evdedir — you are not at her house; you are reasoning from what you know.
Formal generalization / definition (written register). In official, academic, or journalistic writing, -DIr closes a statement of established fact or definition with an authoritative, impersonal tone. Example: Türkiye'nin başkenti Ankara'dır.
Non-past only. -DIr is non-past: it attaches to present-state predicates and, in formal announcements, to future-tense verbs (başlayacaktır «it will begin»). It never combines with past-tense forms — a past inference uses a different construction (evde olmalıydı).
Not for hearsay. If you are reporting what someone else told you, use the evidential -mIş instead. -DIr expresses the speaker's own inference, not second-hand information.
formation
The suffix follows four-way vowel harmony and is written -dır / -dir / -dur / -dür after vowels and voiced consonants, and -tır / -tir / -tur / -tür after voiceless consonants (ç, f, h, k, p, s, ş, t). It attaches to the predicate: a noun, adjective, or locative phrase (evdedir), or — in formal register — a fully tensed verb form, after any person marker (gidiyordur, gelmiştir, başlayacaktır).
A cleaner way to remember the voicing rule: look only at the final consonant of the predicate. If it is one of ç f h k p s ş t, use -tIr; otherwise use -dIr. Vowel harmony then selects the correct vowel (ı / i / u / ü).
| predicate | final sound | suffix | result |
|---|---|---|---|
| evde (at home) | e — voiced | -dir | evdedir |
| hasta (ill) | a — voiced | -dır | hastadır |
| doktor (doctor) | r — voiced | -dur | doktordur |
| güzel (beautiful) | l — voiced | -dir | güzeldir |
| sabit (fixed) | t — voiceless | -tir | sabittir |
| açık (open) | k — voiceless | -tır | açıktır |
| meşgul (busy) | l — voiced | -dür | meşguldür |
examples in context
common pitfalls
Confusing -DIr (assumption) with -mIş (hearsay).
Both express non-direct knowledge, but they differ in source. -DIr signals the speaker's own inference or reasoning: Yorgun olmalı — evdedir. «She must be tired — she's probably home.» -mIş signals information received from another source: Evdeymiş. «Apparently she's home (someone told me).» Using -DIr for hearsay misrepresents the source of your information.
Using -DIr in casual speech for a plain known fact.
If you know for certain that your friend is home — you can see her — saying evdedir sounds either overly formal or oddly uncertain. The bare predicate evde is the natural choice in conversation. Reserve -DIr for inference or formal writing.
Attaching -DIr to a past predicate.
Forms like *evdeydir (attempting to stack -DIr onto a past copula) are ungrammatical. -DIr is a non-past suffix. To express past-tense inference, Turkish uses different constructions (e.g. evde olmalıydı). Do not combine -DIr with past-tense endings.