The term 'chemical endings' refers to the suffixes that are added to the end of chemical names. The crossword solutions INES (4 letters), ENES (4 letters), OLS (3 letters), IDES (4 letters), and YNES (4 letters) are all examples of these chemical endings. INES is a suffix used to denote an organic compound containing a nitrile group, ENES is a suffix used to denote an alkene, OLS is a suffix used to denote an alcohol, IDES is a suffix used to denote an acid, and YNES is a suffix used to denote an alkane.