The word "glis" is quite uncommon, and it might be challenging to find its synonyms. However, some words that could be used in place of "glis" are "gleam," "glisten," "glint," "sparkle," and "shimmer." These terms all relate to the idea of shining or reflecting light. Depending on the context in which you're using "glis," you could also consider alternatives like "flicker," "flash," "twinkle," or "radiance." All of these words add more detail and color to descriptions that involve light, and they will hopefully help you communicate more effectively whatever point you are trying to convey.