o̲

Etymology
Origin sv. Possibly:


 * To visually enhance to clarify its separation from surrounding letters and words. Confer with 🇨🇬, 🇨🇬, and 🇨🇬.
 * An.
 * A continued evolution of & or o., similar to how @ developed from à.

The Language Council of Sweden believes that the first explanation, to visually enhance, is most likely the correct one. But also acknowledges that the second explanation, an, may have played a part.

Conjunction

 * 1) &, and