different between vacuousness vs vacuate

English

vacuous +? -ness

vacuousness (uncountable)

vacuate (third-person singular simple present vacuates, present participle vacuating, simple past and past participle vacuated)

To empty; to clear out.
- 1861, W. R. Wilde, On Aural Diagnosis and Diseases of the Mastoid Process, in The Medical Times and Gazette, volume 1, page 488
  Mr. Toynbee recommends, in cases of ruptured membrane tympani, "directing the stream of water [in syringing] through the orifice of the membrane into the tympanum in oder to vacuate the latter cavity of its contents."

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