bolus

In reference to: 1) Relatively large quantity of substance intended for therapeutic use, e.g., bolus dose of a drug injected intravenously. 2) A masticated morsel of food or another substance ready to be swallowed, e.g., bolus of barium for x-ray studies. 3) In radiology, rapid injection of a large dose of contrast medium to increase opacification of blood vessels. [Latin from Greek, bolos = lump, clod]

References

Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999.