| vacuum extractor | Device for producing traction upon the head of a foetus by means of a soft cup held by a vacuum. (05 Mar 2000) |
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| vacuum flask | <apparatus> A glass vessel, often silvered, with two walls, the space between which is evacuated; used for maintaining materials at constant temperature or, more usually, at low temperature. Synonym: vacuum flask. (05 Mar 2000) |
| vacuum headache | Headache due to closure of the frontal sinus. (05 Mar 2000) |
| vacuum pan | A device for growing crystals from solutions by gradually lowering the pressure within the sealed container holding the liquid. (09 Oct 1997) |
| vacuum tube | A glass tube from which the air has been removed, containing two or more electrodes, between which passes an electrical current or spark; used in the production of X-rays, or to control circuits. Previously in wide use, the vacuum tube has been supplanted by transistors in electronic circuits. (05 Mar 2000) |