The word "ither" is a variant of the word "either". The difference lies in the pronunciation of the initial vowel sound; "either" begins with the diphthong /ai/, while "ither" begins with the monophthong /ɪ/. The IPA phonetic transcription for "ither" is /ˈɪðər/. Although "ither" is generally considered to be nonstandard or dialectal, it is still used in some varieties of English, particularly in Scotland and Northern Ireland.
The word "ither" is derived from the Middle English word "ither", which was a variant of the word "other". In turn, "other" can be traced back to the Old English word "ōþer". The Old English word was closely related to the Old High German word "andar" and the Old Norse word "annarr", both of which also meant "other". The root of these words can be traced back to the Proto-Germanic language, where it had the form "*anþ-, *anadaz". Ultimately, the word can be traced back to the Proto-Indo-European root "*ant-", meaning "front, forehead, before" or "against". Over time, through various linguistic changes, the Old English word "ōþer" developed into the Middle English word "ither".