The scientific study of human movement.

*Kinesiologists* study the acquisition of motor skills, the mechanical aspects of movement, and the body's responses to physical activity. A kinesiologist may work in a public-school fitness program, design exercise programs for people with and without disabilities, or work with patients recovering from disease, accidents, and surgery. As a field of research, kinesiology focuses particularly on the mechanics of muscular activity.

(1) Relating to or affected with hyperactivity. (2) Characterized by fast-paced or frantic activity.

Since the prefix *hyper-* means “above, beyond”, *hyperkinetic* describes motion beyond the usual. The word is usually applied to children, and often describes the condition of almost uncontrollable activity or muscular movements called *attention-deficit/hyperactivity disorder* (ADHD). Kids with ADHD are usually not just hyperkinetic but also inattentive, forgetful, and flighty. Though they're often treated with drugs, many experts believe there are better ways of dealing with the problem. Lots of people now shorten both *hyperactive* and *hyperkinetic* to simply *hyper* (“He's been hyper all morning”), but usually don't mean it too seriously.

A motion picture made from an image on a picture tube.

Kinescope, originally a trademark for the cathode-ray tube in a TV, later became the name for a film of a TV screen showing a live broadcast. In order for a program to be seen beyond New York in the early days of TV, a kinescope had to be shipped from station to station. Though grainy and fuzzy, these were for a time the only way of capturing live shows. But in 1951 Desi Arnaz and Lucille Ball decided to film their comedy show rather than to broadcast it live, and in a few years live broadcast comedy and drama had vanished from the airwaves.

The movement of objects without contact or other physical means, as by the exercise of an occult power.

*Tele-* in Greek means “far off”. The eternally appealing idea of moving an object remotely, using only psychic powers, has had a long life in films, TV shows, stories and novels, video games, and comics. But although some researchers believe in the existence of telekinesis (also known as *psychokinesis*), most scientists believe that any reported experiences have been the result of fraud, wishful thinking, or naturally explainable events.

(1) Relating to physical force or energy. (2) Continuously and productively active and changing; energetic or forceful.

*Dynamic* is the opposite of *static,* which means “not moving or active.” So all living languages, for example, are dynamic rather than static, changing from year to year even when they don't appear to be. A bustling commercial city like Hong Kong is intensely dynamic, constantly changing and adapting. A dynamic relationship—for example, the relationship between housing values and interest rates charged by banks—is one that changes all the time. Unfortunately, the word has been used so much by advertisers that we tend to forget its basic meaning.

(1) A power generator, especially one that produces direct electric current. (2) A forceful, energetic person.

The dynamo was introduced in 1832 to produce electricity for commercial use. Like all later generators, the original dynamos changed mechanical energy (produced by steam, which was itself produced by burning coal) into electricity. The word is less used today than it once was, since it's often applied only to generators that produced direct electric current (DC) rather than alternating current (AC), which is now the standard. A human dynamo is a person who seems to have unlimited energy, such as New York's legendary mayor Fiorello La Guardia, whose forcefulness and vigor matched that of his intensely *dynamic* city.

(1) A science that studies the movement of gases such as air and the way that objects move through such gases. (2) The qualities of an object that affect how easily it is able to move through the air.

Aerodynamics began as a science around the time of the Wright brothers' first manned flights. Since then, it's become important to the building not only of aircraft and automobiles but also of rockets and missiles, trains, ships, and even such structures as bridges and tall buildings, which often have to withstand strong winds. An *aerodynamic* vehicle is one whose design helps it achieve the greatest speed and most efficient use of fuel. But although we might casually call any sleek car design aerodynamic, true aerodynamics is practiced not by artistic product designers but instead by highly trained scientists, and many people's lives depend on their work.

Bernoulli's principle, which is basic to the science of *hydrodynamics,* says that the faster a fluid substance flows, the less outward pressure it exerts. It shows the close relationship between *hydrodynamics* and *aerodynamics* (which deals with the movement of air and other gases), since it can partly explain how air will “lift” an airplane by the way it flows over the wings, and how a spoiler helps keep a race car's wheels pressed to the ground as it accelerates. Hydrodynamics is sometimes applied today in studying the surface of the planets and even the stars. As used informally by boaters, *hydrodynamic* often means “hydrodynamically efficient.”