Sefstrom named the element vanadium after Vanadis, an Old Norse byname of Freyja, the Norse goddess of beauty, love and fertility. He chose her because vanadium forms compounds of striking and varied colour, running through greens, blues, violets and yellows depending on their oxidation state, a beauty he thought worthy of the goddess. The naming is a rare instance of Norse rather than Greek or Roman mythology entering the periodic table, and it stands alongside thorium, named for Thor, as a Scandinavian chemist's tribute to the gods of the north. The choice is symbolic and aesthetic, honouring the colours of the compounds rather than any property of the metal itself.
Freyja is one of the most vivid figures of Norse mythology, associated with love, beauty, war and seidr magic, and Vanadis was among her several bynames, so Sefstrom's choice drew on a genuinely different mythological well than the Greek and Roman names that dominate the rest of the table. Vanadium also has a strange foothold in biology: certain marine invertebrates called ascidians, or sea squirts, concentrate vanadium in their blood cells at levels far above that of seawater, for reasons still not fully understood, giving them blood that can appear green rather than the iron-based red of vertebrate blood.