Definition of bolus in English:



  • 1A small rounded mass of a substance, especially of chewed food at the moment of swallowing.

    ‘mucin holds the particles of food together in a ball or bolus’
    • ‘It's a little too raw and undigested at the moment: a massive bolus in my throat.’
    • ‘After passing the pharynx during swallowing, the food bolus enters the esophagus, which is positioned at approximately the level of the sixth cervical vertebra.’
    • ‘The cardiac sphincter opens because of increasing pressure in the esophagus from the food bolus.’
    • ‘I said, nonchalantly gulping down a bolus of fear.’
    • ‘The tongue directs the bolus of chewed food to the pharynx as an initial step in the involuntary reflex swallowing mechanism.’
    • ‘The goal is a reduction in the resting pressure to allow passage of the food bolus into the stomach.’
    • ‘People swallow quite fluid boluses most of the time, and they do so seated with the trunk upright.’
    • ‘It is important in the lubrication of food boluses, and the amylase in saliva begins the digestion of starches.’
    • ‘Unfortunately, the bacon lump was much larger than I expected, and as a half-chewed bolus disappeared down my throat, I realised I wouldn't be able to swallow it.’
    • ‘Successively, ingestion, food transport to the processing teeth, chewing and bolus formation, and swallowing can be recognized.’
    • ‘The program recorded the video as one gigantic bolus, and pretended that the clips were discrete files, which they weren't.’
    • ‘During summer and autumn, jays routinely make hundreds of food caches per day, placing each saliva-coated bolus in a separate arboreal site.’
    • ‘I swallowed the bolus of spittle that was rising in my throat.’
    • ‘Peering then through the glass, which demarcated the realms wherein we exist, I felt the bolus of grief form in my gullet.’
    • ‘The power supply then plugs into that, giving me a very long power cable with a bolus of electrical tape in the middle.’
    • ‘On Midway Island in the Hawaiian chain, a bolus, or mass of chewed food, coughed up by one bird included many identifiable objects.’
    • ‘Patients may succeed in passing the food bolus by repeated swallowing, by performing the Valsalva maneuver or by making a positional change.’
    • ‘In preparation for swallowing, a softened or liquid food bolus is moved through the mouth by the action of the tongue.’
    • ‘The new thinking is that when you take in a small bolus of protein before exercise, essentially you're giving that protein time to break down while you're working your muscles.’
    • ‘Parent tree swallows deliver food to nestlings in a bolus, making it difficult to determine either the quantity or quality of food.’
    • ‘Once the bolus enters the pharynx, it is transported distally in a structure that can be described as a tubular conduit.’
  • 2A type of large pill used in veterinary medicine.

    • ‘Subsequently, the bolus is transferred to the digestive tract where it is chemically reduced.’
    • ‘This may be due to a large bolus of concentrated solute reaching the myocardium.’
    • ‘Forage intake was estimated at Stillwater using slow-release chromic oxide boluses to estimate fecal output.’
    • ‘All cows with a fever were administered a non-antibiotic regimen of aspirin boluses and probiotic capsules.’
    pill, capsule, lozenge, caplet, pastille, pellet, drop, ball
    View synonyms
    1. 2.1Medicine A single dose of a drug or other medicinal preparation given all at once.
      • ‘Typically, local anesthetics and opiates, alone or in combination, are administered through the epidural catheter as an infusion or a bolus to provide analgesia.’
      • ‘Trials using high concentration boluses of anaesthetic instead of infusions were excluded.’
      • ‘During the night, he became hypotensive, with minimal response to boluses of normal saline.’
      • ‘Of the eight legs injected with a single 30-ml bolus of dye, seven developed high pressures and one did not.’
      • ‘For an allergic person, a small amount of caffeine acts like a bolus, generating abnormal psychological response, including mania.’
      • ‘An IV bolus of 3-5 g arginine reduced blood pressure and platelet aggregation in patients with type 1 diabetes.’
      • ‘No data have been reported on the absorption of morphine and other medications added to the fluid bag or given as a bolus.’
      • ‘Intravenous insulin boluses probably fail because of the short half-life of insulin (ie, approximately five minutes).’
      • ‘The drug bolus was followed by continuous infusion of 50 g/kg/hour until the experiment ended at 48 hours.’
      • ‘This has a greater efficacy than a single, large bolus does.’
      • ‘Treatment was given intravenously as a bolus for the lowest two doses and as a 30-minute infusion for the two highest doses.’
      • ‘The recommended dose for patients with cardiac arrest is 300 mg given intravenously as a bolus.’
      • ‘We are going to gain venous access and give your baby a fluid bolus because she is shut-down’
      • ‘We found that patients receiving continuous infusions were more deeply sedated than were patients managed with boluses or no sedation, as indicated by both lower SAS scores and lower BIS values.’
      • ‘A low power laser warms the targeted tissue and releases a bolus of photosensitizer.’
      • ‘The most common error was injecting bolus doses faster than the recommended speed of 3-5 minutes.’
      • ‘Although there are few data on nicotine lethality, one report suggests that a bolus of less than I mg/kg is fatal in humans.’
      • ‘Some intravenous trials used 1-2 g magnesium sulfate alone, while others used a similar dose as an initial bolus, followed by slower drips over the next few hours.’
      • ‘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.’
      • ‘Upon arrival, he experienced a severe bout of hypotension that was to be treated with a saline bolus.’


Mid 16th century (denoting a large pill): via late Latin from Greek bōlos ‘clod’.