Why was "tantrum" trending last week?
also mock-up, "model, simulation" 1919, perhaps World War I, from mock (v.) + up (adv.). The verbal phrase mock up is attested from 1911.
: blend computer-generated imagery and full-size mock-up dinos seamlessly
A model; a simulation, often full-sized: They made a mock-up of the wing to study the lift (1920+)