The term 'cut into glass' refers to a process of etching or engraving a design onto a glass surface. The crossword solutions for this term are 'ETCH' (4 letters) and 'etched' (6 letters). Etching is a process of using a sharp tool to carve a design into the surface of the glass, which can then be filled with paint or other materials to create a decorative effect. Etched glass is often used in decorative pieces such as windows, mirrors, and vases.