Step 1: Understanding the Concept:
Monosaccharides possess trivial nomenclature based on their natural occurrence and biological functions.
Step 2: Detailed Explanation:
Galactose is a constituent of glycolipids, cerebrosides, and gangliosides, which form essential structural components of the myelin sheath in the brain and central nervous system, earning it the common name 'brain sugar'.
Glucose is known as grape sugar, fructose as fruit sugar, and maltose as malt sugar.
Step 3: Final Answer:
Hence, galactose is also known as brain sugar.