mass
n. C / Un. a large amount of something that has no clear shape. It can also mean the amount of physical matter in an object.
n. a large body of matter with no definite shape; in physics, the quantity of matter in a body regardless of its volume or any forces acting on it.
The clouds formed a dark mass in the sky.
The doctor found a small mass in the patient's lung during the routine scan.
In Newtonian physics, mass is treated as a constant property of an object, whereas in relativistic contexts, it is understood to increase as the object approaches the speed of light.
From Middle English messe, from Old English mæsse and Old French messe, both from Late Latin missa, from Latin mittō (“to send, dismiss”), compare French messe. In the ancient churches, the public services at which the catechumens were permitted to be present were called missa catechumenorum, ending with the reading of the Gospel. Then they were dismissed with the words: "Ite, missa est", the congregation is dismissed. After that the sacrifice proper began. At its close the same words were said to those who remained. So the word gave the name of Mass to the sacrifice in the Catholic Church. Compare Christmas, Lammas, missal. Doublet of missa.
Short forms.
Countable when referring to a specific physical lump or growth; uncountable when referring to the general property of matter in physics.