The word "xerocollyrium" is a mouthful to pronounce and has an unusual spelling. It is pronounced /ˌzɛrəˈkɒlɪriəm/ with the stress on the second syllable. The "xero-" prefix means dry or arid, while "collyrium" is an old term for an eye lotion. Xerocollyrium, therefore, refers to an eye drop or cream that is used to treat dry eyes. Despite the complex spelling and pronunciation, this term has found its way into medical jargon and is recognized by healthcare professionals.
An eye-salve, a non-liquid collyrium.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.