Allow to Deteriorate is a phrase that describes the act of not taking care of something, which can lead to it becoming worse over time. The two crossword solutions for this phrase are NEGLECT (7 letters) and LETSLIDE (8 letters). NEGLECT means to fail to take proper care of something, while LETSLIDE means to allow something to pass without being noticed or corrected. Both words describe the same concept of not taking care of something, which can lead to it deteriorating over time.