keskiviivaa

Keskiviivaa is a Finnish noun meaning "center line" or "midline." It is formed from keski ("middle") and viiva ("line"). The form keskiviivaa is the singular partitive, used in contexts such as negation, quantities, or when describing action affecting part of the line (for example, "keskiviivaa ei saa ylittää" — "the center line must not be crossed").

In traffic and road engineering, keskiviiva denotes the painted line dividing opposing lanes. Variants include katkaistu keskiviiva (dashed center line), which usually permits overtaking when safe, and yhtenäinen tai täysi keskiviiva (solid center line), which generally forbids crossing. Finnish road traffic regulations and guidance define markings and their meanings, and the term appears in signage, manuals, and accident reports.

Beyond roads, keskiviiva is used in anatomy and geometry to indicate a central axis or line of symmetry, such as the body's median plane or the midpoint axis of a shape. In technical drawing and optics it can denote reference lines for measurements.

Grammatically, keskiviiva declines according to Finnish noun paradigms (plural keskiviivat, partitive singular keskiviivaa), and appears in compound terms and technical vocabulary. Its usage spans everyday speech, legal texts, and specialist fields where a clear notion of a dividing or reference line is required.