Glossary
Motion Sickness Glossary
Plain-English definitions for every term you'll run into reading about motion sickness, vestibular disorders, and the available treatments. Written for general readers and aligned with standard medical sources.
Jump to a term
- Motion Sickness
- Car Sickness
- Seasickness
- Airsickness
- Cybersickness (VR Sickness)
- Vestibular System
- Sensory Mismatch
- Semicircular Canals
- Otolith Organs
- Sound Therapy
- Dimenhydrinate (Dramamine)
- Meclizine (Bonine)
- Scopolamine
- Acupressure Wristband
- Sopite Syndrome
- Mal de Débarquement Syndrome (MdDS)
- Vestibular Migraine
- Sea Legs
- VR Legs
- Motion Cues
- Area Postrema
- Motion Sickness
- A common condition caused by a sensory mismatch between the inner ear (which detects motion) and the eyes (which may see a still view). The brain interprets the disagreement as poisoning and triggers nausea as a defense. Also called kinetosis or travel sickness.
- Car Sickness
- Motion sickness experienced specifically in cars. Most common in children aged 2-12 and backseat passengers. Often triggered by reading or phone use during travel.
- Seasickness
- Motion sickness on boats and ships, caused by rolling and pitching motion. Roughly one in four cruise passengers experiences some seasickness. Bigger ships and midship low-deck cabins produce less perceived motion.
- Airsickness
- Motion sickness on airplanes, most often during turbulence and descent. Window-seat passengers over the wing typically feel the least motion.
- Cybersickness (VR Sickness)
- Motion sickness from virtual reality. Caused by the reverse sensory mismatch: the eyes see motion but the body stays still. Affects an estimated 40-70% of new VR users; most develop tolerance ("VR legs") within 2-4 weeks of regular use.
- Vestibular System
- The sensory system in the inner ear that tracks motion, balance, and spatial orientation. Consists of three fluid-filled semicircular canals plus two otolith organs in each ear - five sensors total per side.
- Sensory Mismatch
- The fundamental cause of motion sickness. Occurs when the vestibular, visual, and proprioceptive systems give the brain conflicting reports about body motion. The brain pattern-matches this to ancient poisoning signals and triggers nausea.
- Semicircular Canals
- Three small fluid-filled hoops in each inner ear, oriented at right angles. They detect rotational motion of the head by sensing how fluid sloshes against hair cells.
- Otolith Organs
- Two structures in each inner ear (utricle and saccule) containing calcium-carbonate crystals that detect linear acceleration and gravity. Sound therapy works in part by stimulating these organs.
- Sound Therapy
- The use of calibrated audio to influence physiological processes. For motion sickness, calibrated low-frequency tones stimulate the inner ear's otolith organs to give the vestibular system a clear reference and shrink the sensory mismatch. Used in apps like Dizzout.
- Dimenhydrinate (Dramamine)
- An over-the-counter antihistamine used to prevent motion sickness. Onset 30-60 minutes. Causes significant drowsiness; not recommended for drivers.
- Meclizine (Bonine)
- An over-the-counter antihistamine for motion sickness. Slower onset than Dramamine but longer duration (up to 24 hours) and less sedating.
- Scopolamine
- A prescription anticholinergic medication, typically delivered via a transdermal patch applied behind the ear. Lasts up to 72 hours. Side effects include dry mouth and blurred vision. Not recommended during pregnancy.
- Acupressure Wristband
- A band designed to press the P6 acupressure point on the inner wrist, reported by many users to reduce nausea. Sea-Bands is the most common brand. Evidence is mixed; risk profile is zero.
- Sopite Syndrome
- A subtle form of motion sickness with drowsiness, fatigue, low motivation, and mood changes instead of nausea. Often unrecognized because it lacks the classic symptoms.
- Mal de Débarquement Syndrome (MdDS)
- A rare condition where the rocking or swaying sensation persists for days, weeks, or months after disembarking from a cruise or other long voyage. Distinct from seasickness itself; tends to fade on its own but can require vestibular therapy.
- Vestibular Migraine
- A type of migraine featuring episodes of vertigo or motion sensitivity, with or without typical migraine headache. Affects roughly 1% of the population. Sufferers are usually more prone to ordinary motion sickness as well.
- Sea Legs
- Colloquial term for the adaptation to ship motion that develops over hours to days at sea. Once "sea legs" set in, motion sickness usually resolves for the duration of the voyage.
- VR Legs
- Colloquial term for the tolerance to VR motion that develops over 2-4 weeks of regular use. Once a user has "VR legs," cybersickness usually diminishes substantially.
- Motion Cues
- Visual cues that help the brain anticipate motion. Apple's iOS 18 Vehicle Motion Cues feature (launched 2024) adds animated dots to the phone screen that respond to vehicle motion, reducing the sensory mismatch when reading in a car.
- Area Postrema
- A small region in the brainstem that sits outside the blood-brain barrier and acts as a chemical and signal alarm. It is the brain area that triggers nausea in response to vestibular sensory conflict (and to actual toxins).