öinni

æðinni is a term in Icelandic anatomy referring to a blood vessel in the definite form of æð. The base noun æð designates a blood vessel; in practice Icelandic uses slagæð for artery and bláæð for vein. The indefinite/definite forms are used according to standard Icelandic grammar. In modern medical language, æð alone is rarely used; instead, specific terms are preferred. The word's etymology traces to Old Norse æð, with cognates across Nordic languages. In historical Icelandic texts, æð sometimes appears in descriptions of the circulatory system before the modern terminological shift to slagæð and bláæð. The circulatory system consists of arteries (slagæðar), veins (bláæðar), and capillaries (háræðar). The use of æðinni as a definite form is primarily grammatical; it does not denote a separate anatomical structure beyond the general concept of a vessel. See also: slagæð, bláæð, háræð, vascular system, angiography.