This is the 13202nd most frequent Russian word.
минувший
"Минувший" means "past" or "gone by."
The word 'минувший' is used as an adjective in its past participial form to describe the preceding Monday.
В минувший понедельник мы гуляли по парку.
Last Monday, we walked in the park.
'Минувшие' acts as an adjective describing a period of time (years) that has already passed.
Минувшие годы оставили одни из лучших воспоминаний.
The past years left some of the best memories.
Here, 'минувшей' is the feminine singular form of 'минувший' used to modify a feminine noun ('недели').