A mass unit is a term used to describe the measurement of the mass of an object or substance. Synonyms for mass unit include weight unit, gram, kilogram, pound, and ounce. A weight unit is a measurement commonly used in the United States that represents the force of gravity on an object. A gram is the basic unit of mass in the metric system, while a kilogram is a larger unit of mass equal to 1000 grams. A pound is an imperial unit of mass, while an ounce is a smaller unit of mass that is commonly used in cooking and other applications. Overall, there are many different synonyms that can be used to describe a mass unit depending on the context and application.