Yearlong

Yearlong is an adjective describing something that lasts for the duration of a calendar year or spans twelve months. It is commonly used for projects, programs, events, and studies that extend over the full annual period rather than shorter timeframes.

In usage, yearlong is often written as a hyphenated compound when placed before a noun (year-long project). In contemporary English, yearlong is also increasingly seen as a single word. Predicative constructions are less common; more natural phrasing tends to say that something lasted a year or lasted the whole year, rather than using yearlong in a predicate position.

Examples include a yearlong project, a yearlong course, and a yearlong celebration. The term emphasizes the temporal scope of twelve months and is distinct from related terms such as annual or twelve-month, which can convey recurrence or a fixed twelve-month period rather than ongoing duration.

Etymology: yearlong is formed from the noun year and the adjective long. It is a modern compound whose preferred spelling varies by style guide and regional usage. See also calendar year, fiscal year, twelve-month period, and annual for related concepts of time measurement and duration.