Definition of bolus in English:

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Pronunciation: /ˈbōləs/

noun (plural boluses)

1A small rounded mass of a substance, especially of chewed food at the moment of swallowing.
Example sentences
  • After passing the pharynx during swallowing, the food bolus enters the esophagus, which is positioned at approximately the level of the sixth cervical vertebra.
  • On Midway Island in the Hawaiian chain, a bolus, or mass of chewed food, coughed up by one bird included many identifiable objects.
  • Successively, ingestion, food transport to the processing teeth, chewing and bolus formation, and swallowing can be recognized.
1.1A type of large pill used in veterinary medicine.
Example sentences
  • All cows with a fever were administered a non-antibiotic regimen of aspirin boluses and probiotic capsules.
  • Forage intake was estimated at Stillwater using slow-release chromic oxide boluses to estimate fecal output.
  • Subsequently, the bolus is transferred to the digestive tract where it is chemically reduced.
1.2 Medicine A single dose of a drug or other medicinal preparation given all at once.
Example sentences
  • Our analysis shows that the two weak stages in the system are drugs that require multiple step preparation and administration of doses as a bolus.
  • The drug bolus was followed by continuous infusion of 50 g/kg/hour until the experiment ended at 48 hours.
  • Treatment was given intravenously as a bolus for the lowest two doses and as a 30-minute infusion for the two highest doses.


Mid 16th century denoting a large pill of medicine: via late Latin from Greek bōlos 'clod'.

Words that rhyme with bolus

Aeolus, alveolus, bolas, gladiolus, holus-bolus, solus, toeless

For editors and proofreaders

Syllabification: bo·lus

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