The word 'epiousion' in the Lord's Prayer is a Koine Greek adjective with an unclear meaning, traditionally translated as 'daily' but rejected by most modern scholars. The word's meaning relies on morphological analysis and context, with alternative theories including 'supersubstantial', 'necessary for existence', and 'for the future'. The Catholic Church and Eastern Orthodox Church have different interpretations of the word, with the former considering 'supersubstantial' a literal translation and the latter viewing it as 'more-than-necessary bread'. The word's meaning has been debated by scholars and theologians for centuries.