seríunnar
Seríunnar is a term that can refer to several related concepts, primarily within the context of astronomy and celestial observation. In its most common astronomical usage, it pertains to a hypothetical celestial body or phenomenon that has been proposed to explain certain observed anomalies in the orbits of planets or other celestial objects. Historically, the idea of an unseen planet, sometimes referred to as "Seríunnar" or a similar designation, was posited to account for irregularities in the motion of Uranus, which eventually led to the discovery of Neptune. This type of theoretical object is often conceived as existing beyond the known planets, influencing their gravitational fields.
The term can also be used more broadly in speculative or fictional contexts to describe a planet,