(Irregular plural: masses).
1. A large body of matter without definite shape.
2. An ill-structured collection of similar things (objects or people).
3. The property of a body that causes it to have weight in a gravitational field.

1. To join together into a mass; collect or form a mass; of crowds of people
2. To form or collect into a mass
3. To assemble in a mass

1. Occurring widely (as to many people); SYN. large-scale.
2. Viewed as a whole; total

In music, the setting of the invariable parts of the Christian Mass, that is the Kyrie, Gloria, Credo, Sanctus with Benedictus, and Agnus Dei. A notable example is J S Bach’s Mass in B Minor.
In Christianity, the celebration of the Eucharist.
1. A musical setting for a Mass.
2. The celebration of the Eucharist (in the Roman Catholic Church and some Protestant Churches).

In physics, the quantity of matter in a body as measured by its inertia. Mass determines the acceleration produced in a body by a given force acting on it, the acceleration being inversely proportional to the mass of the body. The mass also determines the force exerted on a body by gravity on Earth, although this attraction varies slightly from place to place. In the SI system, the base unit of mass is the kilogram.
At a given place, equal masses experience equal gravitational forces, which are known as the weights of the bodies. Masses may, therefore, be compared by comparing the weights of bodies at the same place.
The standard unit of mass to which all other masses are compared is a platinum-iridium cylinder of 1 kg, which is kept at the International Bureau of Weights and Measures in Sčvres, France.