úasti

Could you specify what you mean by "úasti"? There isn’t a widely recognized topic by that exact title in English-language reference works. It could refer to a term in Irish history or language, a place name, a personal name, or something else. If you can provide more context (for example, whether it’s a Gaelic word related to land holdings, a geographical location, or a modern use), I can draft a concise, neutral wiki-style article under 300 words.