Whiplash is a non-medical term describing a range of injuries to the neck caused by or related to a sudden distortion of the neck associated with extension, although the exact injury mechanisms remain unknown. The term "whiplash" is a colloquialism. "Cervical acceleration–deceleration" (CAD) describes the mechanism of the injury, while the term "whiplash associated disorders" (WAD) describes the subsequent injuries and symptoms.

Whiplash is commonly associated with motor vehicle accidents, usually when the vehicle has been hit in the rear; however, the injury can be sustained in many other ways, including headbanging, bungee jumping and falls. It is one of the most frequently claimed injuries on vehicle insurance policies in certain countries; for example, in the United Kingdom 430,000 people made an insurance claim for whiplash in 2007, accounting for 14% of every driver's premium. In the United States, it is estimated that more than 65% of all bodily injury claims are whiplash related, translating to around $8 billion in economic costs per year.

Before the invention of the car, whiplash injuries were called "railway spine" as they were noted mostly in connection with train collisions. The first case of severe neck pain arising from a train collision was documented around 1919. The number of whiplash injuries has since risen sharply due to rear-end motor vehicle collisions. Given the wide variety of symptoms associated with whiplash injuries, the Quebec Task Force on Whiplash-Associated Disorders coined the phrase 'Whiplash-Associated Disorders'.

While there is broad consensus that acute whiplash is not uncommon, the topic of chronic whiplash is controversial, with studies in at least three countries showing zero to low prevalence, and some academics positing a linkage to financial issues.