The use of âholidayâ to mean âa missed spotâ appears to be that rarity in English etymology, a word or phrase that actually has a nautical origin. The original use of âholidayâ in the âmissed a spotâ sense, back in the 18th century, was in reference to crew members painting the decks of a ship or âpayingâ (sealing seams with tar or pitch) its hull.
The knee jerk reflex is when a tendon above the kneecap is tapped with a reflex hammer, which causes the whole leg to involuntarily jerk.
Definition of Knee jerk. Knee jerk: The reflex that is tested by tapping just below the bent knee on the patellar tendon. Normally this causes the quadriceps muscle to contract and bring the lower leg forward. It has given rise to the saying 'a knee-jerk reaction.' Also known as patellar reflex. Last Editorial Review: 5/13/2016.