Entry 3 senses · 2 variants Webster, 1913 Muller /mŭl'-ẽr/ · Mull·er · IPA /ˈmʌləɹ/ n. n. 01 n. One who, or that which, mulls. 1. One who, or that which, mulls. 2. A vessel in which wine, etc., is mulled over a fire. 02 n. A stone or thick lump of glass, or kind of pestle, flat at the bottom, used for grinding pigments or drugs, etc., upon a slab of similar ma… 1. A stone or thick lump of glass, or kind of pestle, flat at the bottom, used for grinding pigments or drugs, etc., upon a slab of similar material.