hook: A term used to describe the flight of a hit ball with a outside-in swing path. The batter hits the outside of the ball pulling it . This produces sidespin causing the ball to curve violently toward the line.
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inertia: A term that describes an objects resistance to change position and is proportional to its mass. This concept is explained in Newton’s First Law of Motion, “an object in motion (or at rest) tends to stay in motion (or at rest), unless acted upon by an outside force”. Hitters without motion or rhythm in their stance have to overcome inertia to get their swing started.
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jammed: A term used to describe contact made just above the hands on the bat handle. Hitters often get jammed on a inside fastball if they have long, sweeping swings. In order to hit the ball with the barrel, they must make contact well out in front, usually pulling the ball . Being too late, exposes the handle, resulting in contact just above the hands causing vibration. Some hitters using metal bats are strong enough to still carry the ball over the infielders when jammed. When using wooden bats, hitters getting jammed normally results in a broken bat. This is one of the biggest adjustments that hitters make going into pro ball. Hitters with short, compact swings have less difficulty in making adjustments to wooden bats.

kinetic energy: Energy due to an objects motion. The formula for kinetic energy is KE = 1/2 mv2 where m stands for mass and v represents velocity. This formula has great implications for understanding the relationship between bat weight and bat speed, and how each factor affects the energy that’s imparted to the ball. Increases to the mass of the bat (weight) are directly proportional to increases in the bat's kinetic energy. By holding velocity constant, and slightly increasing the bat’s mass (weight), we it’s KE would increase proportionately.. However, if we were to hold its mass constant, and increase its velocity, the KE would increase with the square of the velocity. Consequently, picking a bat that we could swing at a higher velocity would have a greater impact on its KE, because KE increases by the square of its velocity . In laymen’s terms, the greater the batspeed, the more power a hitter will have.

knob to the ball: A phrase used by instructors to describe a hand path emphasizing the bottom hand pulling the knob straight to the inside of the ball. As the knob goes down, the barrel stay up, eliminating the problem of dropping the barrel and uppercutting.
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launch position: A term that describes the location of the hands around the back shoulder after loading occurs. The hands move to this position before they go forward. (see also hitch position)
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lever: A simple machine consisting of a long rigid bar. A bat is a lever. Levers are classified according to where the force (f) and resistance (r) are applied in relation to the fulcrum (pivot point). A bat is a third class lever, which is favored for developing speed. Most striking sports such as golf and tennis involve equipment that are third class levers. (golf club, tennis racquet) These levers are used generate high head speeds developing higher kinetic energy, so greater force is transferred to the ball. see bat.
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line drive: A term used to describe hard contact in which the ball travels roughly parallel to the ground for a distance before dropping. Approximately 80% of line drive contact results in hits, versus 20% of fly balls, and 30% of ground balls, respectively.

linear: A term that describes a classification of motion of an object moving in a straight line, as opposed to rotating around a point. (rotation)

linear transfer method: This method of hitting is based on a tremendous weight shift from the back side to the front side. From a side view, the hitter’s center of gravity makes a pronounced move forward during the swing. This style normally results in the head also moving forward as hitters maintain dynamic balance. Less emphasis is placed on a back foot pivot and back hip commitment since the hitter is less dependent of developing force through the rotation of the lower body and hip action. As the weight is received against a firm frontside, the back foot moves forward, and can actually be pulled off the ground at contact. Many feel that this method keeps the barrel through contact longer than the rotational method.
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load: This is a generic term uses to describe a cocking action, which can apply to the hands, bat head, or the hitter’s front side. A load is used to gather gain potential energy, much like pulling a bowstring back to propel an arrow, or taking a backswing in golf or tennis. There are numerous ways hitters load. This action is also used to overcome inertia, to make a smoother action starting the swing. Loading is also an important factor in separating the stride from the swing, and can assist the front side from flying open too soon.
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load, bat: A term that describes the cocking action of the bat at the top, prior to the forward swing beginning. As the barrel end moves toward the pitcher, it has to travel further from contact. Once the barrel moves to a point beyond the top of the head, it is considered to be wrapped, adding unnecessary length to the swing.
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load, inward turn: A type of load where a hitter slightly rotates his body away from the pitcher, closing his front side. This load is used primarily by rotational style hitters. Hitter using an inward turn must make sure that the turning action does not cause head movement which could obscure his vision.
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load the knob: A type of load where hitters move the knob of the bat slightly upward and back. This movement creates a little bat load at the top and closes the front shoulder if the hitter maintains the angle in the front elbow.
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load, no: A type of load in which a hitter makes no movement prior to hitting.

load, preloaded: A type of load in which a hitter cocks the lower body and hands prior to the pitch so their first move is basically forward, toward the ball. This is used more in fastpitch than baseball due to the shorter distance and less time involved from pitcher to plate.
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load, reverse C: A type of load in which the hitter’s hands move through a small backwards C path, first moving back, then up, then back down to the pitch. This also has an effect of loading the barrel and closing the front shoulder.
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load, tiny circles: A type of action that precedes loading the hands. The hitter’s hands move in tiny circles, as if they were drawing small circles with the knob of the bat. This small movement in the hands can be used to overcome inertia, and develop rhythm.
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long-short-long: A mechanical principle used to gather angular velocity in order to propel an object more forcefully. See extension.
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longitudinal axis: A term that describes an imaginary line running down through the top of the head, through the body to the ground. A rotational style hitter’s body parts revolve around this axis.
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lunge: A term that describes a hitter’s forward weight transfer that occurs at the same time of the stride. Lunging does not allow a hitter to separate. Many hitters bring their hands forward with their weight transfer, leaving them nothing to hit offspeed pitches with.
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maintain angle: This phrase is used to instruct a hitter to hold the angle formed in the front elbow constant as they load the hands. Straightening the elbow, or barring the lead arm, can result in a longer swing radius, that could drive the front shoulder open prematurely.
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