(embryology) A mass of cells within a primordial embryo that will eventually develop into the distinct form of a fetus in most eutherian mammals.

(physics, chemistry, dated) Pedantic form of mass number. Symbol: A.

plural of weapon of mass disruption

A weapon used to create large-scale disruption instead of destruction.

Large facilities enabled to vaccinate.

(evolutionary theory, geology) One of five historical events in which the Earth experienced a loss of ∼75% of all species over a geological interval of less than 3 million years, the most recent being the Cretaceous–Paleogene extinction event 66 million years ago.

plural of mass extinction event

plural of mass haul diagram

(construction) A diagram illustrating the amounts of material that will be cut from the terrain and used to fill other areas, for example when building a railway.

(physics) The mass of an object measured via the gravitational force experienced by it in a known gravitational field