Overage, Obsolete, Too Old
noun, verbal noun, の adjective
Elderly people start to decay and they get all decrepit and gross. Like a corpse. Bleh. Good thing I'll never be too old. Ho ho ho!
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
That building is pretty decrepit so you shouldn’t go in it.