Accusative for Duration and Extent

The non-prepositional accusative of time and measure (акузатив времена и мере) is an essential structure across all registers of Serbian.

1. Syntactic Function
Unlike a true direct object (прави објекат), this accusative cannot undergo passivization. Syntactically, its function depends on the governing head:

• Optional adverbial modifier (прилошка одредба): With action or activity verbs, it modifies the clause expressing duration or distance:
  • Durative verbs: спавати (to sleep), радити (to work), чекати (to wait), живети (to live).
  • Verbs of movement: ходати (to walk), трчати (to run), путовати (to travel).
• Obligatory complement (прилошка допуна / објекат мере): With scalar, quantitative, and durational verbs, the measure phrase is grammatically required to complete the verb's valence (e.g., коштати [to cost], тежити [to weigh], трајати [to last]; forms like *Ова књига кошта or *Састанак је трајао are incomplete without the measure).
• Adjectival complement: In combination with dimensional adjectives (e.g., висок [tall], дуг [long], широк [wide]), it functions as an internal modifier or complement within the adjective phrase (e.g., висок два метра, дубок један метар).

2. The Determination Requirement
In standard Serbian, an isolated bare temporal noun cannot usually stand alone in the accusative to express duration (e.g., *Спавао сам ноћ is ungrammatical). The duration phrase must be semantically specified and delimited through one of the following means:

• An adjective or demonstrative modifier: Спавао сам целу ноћ. (I slept all night.)
• A quantifier or numeral: Учио сам три сата. (I studied for three hours.)
• A specifying genitive complement: Остао је годину дана. (He stayed for a year.)
• Coordinated binomial pairs: Idiomatic fixed pairs can appear without modifiers (e.g., Радио је дан и ноћ).

3. Duration, Temporal Localization, and Aspectual Distinctions
It is important to distinguish the different temporal uses of the accusative and how they interact with verb aspect:

• Duration vs. Temporal Point: When determined by a modifier, the bare accusative can fulfill two related temporal functions:
  • Duration answering Колико дуго? (How long?): Спавао је целу ноћ; Радили смо цео дан.
  • Point in time / Localization answering Када? (When?): Отишао је тај дан; Ту ноћ се родио син. Note that in standard Serbian, points in time for larger cycles such as months or years canonically require the temporal genitive (e.g., следећег месеца, ове године) rather than a bare accusative. Furthermore, standalone, undetermined day names cannot stand alone in the accusative to express a point in time; they require у + акузатив (e.g., у среду, у понедељак).
• Aspect and Completed Timeframe vs. Duration: Compare the bare accusative of duration with за + акузатив. This distinction is intimately tied to verb aspect:
  • The bare accusative of duration denotes ongoing, continuous duration over an interval and almost exclusively combines with imperfective verbs: Писао је рад три дана (He was writing / spent three days writing the paper). Using a perfective verb here (*Написао је три дана) is ungrammatical.
  • The prepositional construction за + accusative denotes the time boundary within which an event reaches completion or culminates, canonically requiring a perfective verb: Написао је рад за три дана (He finished writing the paper in three days).