The word "bith" is quite an interesting spelling challenge, as it can be spelled in different ways depending on the language it comes from. In Irish, for example, it is spelled "beith" (pronounced /bʲɛh/), while in Welsh it is spelled "byth" (pronounced /bɪθ/). The spelling "bith" seems to be unique to Middle English, where it was pronounced as /biːθ/. While the spelling may be tricky, understanding the origin and pronunciation of a word can help with proper spelling in any language.