The term 'disintegrate slowly' can be described by two crossword solutions: ROT (3 letters) and ERODE (5 letters). ROT is a verb meaning to decay or decompose, usually due to the action of bacteria or fungi. ERODE is also a verb meaning to wear away gradually, typically as a result of water, wind, or other natural forces. Together, these two words describe the process of something slowly breaking down over time.