aðir

Could you clarify what you mean by "aðir"? In Icelandic, the form is not a common standalone word on its own, but it could refer to different things depending on context (for example, a form related to the adjective "aðrir" meaning "other," or it could be a proper noun like a place or name). If you specify what sense or domain you have in mind (linguistics, geography, a person, a brand, etc.), I can write a concise, neutral wiki-style article under 300 words.