The Navajo word náádamóo is an expression of time. The word damóo, on its own, is the word for Sunday – a term adapted from Spanish domingo.
The prefix – náá – signifies a repeat of some sort, or ‘another one just like it’. For example, náá’ahideeltsééh is a parting expression that means, “I’ll see you (again) later.”
The whole word náádamóo is saying “next Sunday.”
It also means “next week.” Náádamóogo (or náádámóogo) is usually coupled with a day of the week to add specificity.