dummy run
noun phrase

- a practice or trial

(Oxford Dictionary)

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The phrase "dummy run" stems from dummy, as in "not real but having a similar appearance to something else," and "run," which in this context means a practice or a trial.

The term dummy derives from the adjective "dumb," as in a person who is unable to speak. In the mid-19th century this sense was expanded to refer to a figure that represents a person, such as a doll or a mannequin for example. The figures that ventriloquists make appear as if they are talking are also called dummies.

Dumb is also used to describe silent equipment, such as the dumbwaiter, a movable platform for passing dishes up and down from one room to another, especially from the kitchen. The idea here of course is that it acts as a "silent waiter."

While "dumb" originally meant silent, it took on the additional sense of "stupid, ignorant" in the mid-19th century. This change was likely influenced by the German adjective "dumm." Still, a dummy run is usually not a dumb idea.

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POLITICAL CORRECTNESS

Nowadays, because of the double meaning of dumb, many speakers now prefer to use the term "speech impaired" to describe people with talking difficulties.

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SYNONYMS for dummy run

dress rehearsal, dry run, practice run, trial run, test run

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Practice OWAD in a conversation:

"It's always a good idea to do a DUMMY RUN if you have an important presentation to make."