Vbar

Vbar, written as V-bar or V̄, is a notation used in several disciplines to denote either a syntactic projection in linguistic theory or the average value of a variable named V.

In generative linguistics, V-bar theory refers to the intermediate projection of the verb within X-bar syntax. The V-bar level (often labeled V′) sits between the bare verb and the higher projection that hosts the subject and complements. This level encodes the verb plus its selected complements and helps account for transitivity, object placement, and related argument structure phenomena. In later frameworks such as the Minimalist Program, the grammar emphasizes a vP–VP architecture, with external arguments associated with the functional head little v rather than a separate V-bar projection; nevertheless, discussions of V-bar remain common in historical and cross-linguistic descriptions of verb phrase structure.

In mathematics, physics, and statistics, V̄ is routinely used to denote an average or mean value of the variable V, such as the time-averaged velocity v̄ or the ensemble average ⟨V⟩. Depending on the field, V-bar may also designate a reference value, nominal voltage, or baseline in diagrams and specifications.

Although the meaning of Vbar depends on context, it is commonly associated with verb phrase structure in linguistics and with averaging in quantitative disciplines. See also X-bar theory, vP, and minimalist syntax terminology for related concepts.