What is the Irish Gaelic for book house?

There isn't a direct translation for "book house" in Irish Gaelic that captures the meaning of a building specifically for books like a library. You'd need to use a descriptive phrase. Here are a few options, depending on the nuance you want:

* Teach leabhar: This is the most literal translation, meaning "house of books." It's simple and understandable, but doesn't explicitly convey the idea of a library as a public institution.

* Leabharlann: This is the word for "library." It's the most accurate and commonly used term.

Therefore, Leabharlann is the best and most natural-sounding option.