Bowling Definitions Explained

Actual Span- Distance from edge of thumb hole nearest to center, to edge of finger holes nearest to center; including all inserts and/or grips.
Angle of Entry- The angle measured parallel to the boards at which the bowling ball hits the pocket after completing its path down the lane.
Arc- Ball path from foul line to headpin that does not have a sharp, defined break point.
Axis of Rotation- Imaginary line, perpendicular to the track, along which a bowling ball rotates around during its path down the lane.
Axis Point- One of two points located on opposite poles marking the endpoints of the axis of rotation.
Axis Rotation- The degree that the bowler’s axis rotates in the horizontal plane towards the bowler at release.
Axis Tilt- Angle between axis of rotation and the horizontal plane caused by the bowler at the release; represents an angle of the axis of rotation above a horizontal line through the middle of the ball.
Axis Weight- Method of drilling in which the weight block is positioned so that its mass is evenly distributed around the axis of rotation (also referred to as 'pin on the PAP').
Back of Hole- Portion of hole facing away from the center of the grip.
Backend- 15 feet of lane directly preceding the headpin.
Backup Ball- Style of bowling in which the movement of the ball is from left to right for right-handers, and from right to left for left-handers.
Balance Hole- A hole placed in the ball to bring a ball back into ABC static balance specifications.
Ball Reaction- Change in direction of the ball’s path as it travels from foul line to pins.
Bevel- Rounded edge of any hole drilled in a bowling ball.
Boards- Any one of 39 individual strips of wood pieced together to comprise the surface of the lane.
Bottom Weight- Imbalance in which the half of the ball opposite the center of the grip weighs more than the half containing the center of the grip.
Break Point- Point in the trajectory of a bowling ball at which the ball makes its greatest change in direction.
Bridge- Distance between the finger holes.
Caliper- A graduated rule with one sliding jaw and one that is stationary. Used to determine thumb oval sizes.
Callus- Thickened, hardened area of skin caused by build-up due to friction against the skin.
Carry Down- Oil moved down the lane by the bowling ball.
Center Line- Vertical line between the fingers and through the middle of the thumb.
Center Line Transposition-(CLT) Lateral shift of the center line, after drilling thumb first.
Center of Gravity (CG)- The point in a body or system around which the whole mass is concentrated and may be assumed to act. Also, the point on the surface of the bowling ball where static balance is zero in all directions on a do-do scale – usually marked by a logo.
Conventional Grip- Grip in which the bowler places his or her fingers in the ball to the second joint at a 90-degree angle, while placing his or her entire thumb in the ball.
Cosmetic Bevel- Bevel at the extreme top of the hole which provides a neat appearance to the finished hole.
Coverstock- Outer shell of the bowling ball (composition varies; polyester, urethane, reactive resin, particle reactive resin).
Cranker- Bowler who generates revolutions by a cupped wrist, bent elbow or muscled armswing.
Cut to Cut Span- Distance from edge of thumb hole nearest to center, to edge of finger holes nearest to center, excluding all inserts and/or grips.
Deflection- Amount of displacement incurred in a bowling ball’s trajectory after making contact with a headpin.
Degree of Oval- Degree of oval of a hole will be to the center line measured on a horizontal line from the center of the thumb hole.
Differential RG- Difference between the low-RG and high-RG values of any bowling ball.
Dropped Ring Finger- A fit in which the ring finger span is intentionally shortened to be less than the middle finger span.
Dull Finish- Refers to the bowling balls surface texture; created using sandpaper and/or Scotch-Brite pads.
Durometer- Device used to measure the hardness of a bowling ball.
Dynamic Imbalance- Measure of weight in an object in motion.
Dynamics- Characteristics of the mass inside of a bowling ball.
Equator- Line around the ball, perpendicular to the vertical axis and the midline covering the entire circumference of the ball.
Finger Weight- Imbalance which effectively makes the side of the ball, divided by the midline (containing the finger holes), heavier than the side containing the thumb hole.
Flare- Refers to the bowling ball changing its axis of rotation, while seeking its preferred spin axis down the lane. The result is several distinct oil rings, visible around the ball.
Forward Pitch- The drilled hole, either finger or thumb, is angled towards the midline of the grip.
Friction- The resistance to motion of two moving objects or surfaces that touch.
Front of Hole- Portion of the hole facing toward the center of grip.
Full Roller- A bowler whose track passes between the thumb and fingers and whose track measures the circumference of the ball.
Full Span- Distance from edge of thumb hole nearest to center to edge of finger holes nearest to center, including all inserts and grips.
Gripper/Squeezer- Someone who holds on to the ball with excessive force or muscle.
Heads- Portion of the lane from the foul line to the range finders (arrows) and are generally located 15 to 18 feet down the lane.
High Performance- Balls Bowling balls designed to produce specific reactions for different bowlers.
High Track- A track outside of the thumb hole and finger holes that is no more than an inch from either.
Hinge Angle- Angle at which the thumb is connected to the hand.
Hit the Ball- Acceleration of the hand around the ball, from bottom to side, at the release point.
Hook- Amount, measured in boards and angle, that a bowling ball deviates from its original trajectory in its path down the lane.
Hook Angle- Angle at which the bowling ball changes direction at its break point.
Hook Potential- Degree to which the properties designed into a bowling ball and in its potential to traverse during its path down the lane.
Horizontal Axis Measurement- Displacement of the center of gravity from the geometric center of a bowling ball.
Imbalance- Displacement of the center of gravity from the geometric center of a bowling ball.
Inside Line- The portion of the lane bounded by 10 boards on each side.
Label Shift- Displacement of the label from the center of the grip.
Lateral Pitches- Right and left components of hole angle in any drilled bowling ball.
Leverage Position- In bowling, it's the position at which the bowler is able to use his or her body to create rotation, speed and momentum on the bowling ball (balanced position).
Leverage Weight- A drilling in which the center of the weight block is placed at a 45-degree angle to the axis of rotation of the bowler.
Line- Intended path of the ball down the lane.
Loft- Distance the ball travels before actually making contact with the lane surface after the bowler releases the bowling ball.
Low Track- A track outside the finger holes and thumb hole, but more than two inches from either.
Mark- Point on the lane at which the bowler is aiming.
Mass Bias- Weight in a particular area of the ball.
Midline- Line that perpendicularly bisects the center line of the grip. A horizontal line halfway between the fingers and thumb.
Moment of Inertia- Amount of force required to spin an object.
Negative Side Weight- Imbalance in a ball that effectively makes the left side of the ball heavier for right-handed release players, and the right side of the ball heavier for left-handed release players.
Negative Weight- Imbalance which causes thumb, negative side or bottom weight.
Ovaled Hole- The shape of a hole being out of round.
Pin- A small round colored pin in a bowling ball that signifies the top of the core/weight block. Usually colored the same as the engraving paint.
Pin Action- The manner in which the pins react to the impact of the bowling ball.
Pin Shift- The process of creating reaction in a bowling ball by displacing the pin from the axis of rotation or the PAP.
Pitch- The angle at which a hole is drilled into a bowling ball in relationship to the center of the ball.
Pivot Point- Point on the ball’s surface where all track lines intersect.
Positive Axis Point (PAP)- Point on the surface of the ball that signifies the bowlers axis of rotation, on the positive side of the ball.
Positive Side Weight- Imbalance that effectively makes the right side of the bowling ball from the center of grip heavier than the left for right-handed release players, and left side of the ball heavier than the right for left-handed release players.
Positive Weight- Imbalance which causes finger, positive side or top weight.
Preferred Spin Axis (PSA)- The axis about which the bowling ball wants to rotate around.
Radius of Gyration (RG)- An account or measurement of the distribution of the mass in an object from the geometric center.
Release Point- Point in the delivery at which the ball leaves the hand.
Reverse Block- A lane condition in which the inside portion of the lane is covered with less conditioner than the outside.
Reverse Pitch- The drilled hole, either finger or thumb, is angled away from the midline (center) of the grip.
Revolutions- The number of times the bowling ball makes a complete rotation about its axis during its path down the lane.
Safe Zone- The area on the ball from 1 inch inside the vertical axis line to a line from the bowlers PAP to the ring finger and from the PAP to the equator, in which the pin of a ball can be placed safely without the track and holes interfering with one another.
Shell- The outer portion of a bowling ball surrounding the core.
Shiny- A ball that looks glossy; in general, shiny balls are smoother textured.
Skid- The portion of the bowling ball's path in which the velocity of the contact point on the ball is greater than zero, and the ball is not rolling, but is instead sliding down the lane.
Snap- A ball path which has a sharp, defined break point; however, when referring to the actual break point, the term snap is often used as a quantifying term.
Span- Distance from edge of thumb hole nearest to the center, to the edge of finger holes nearest to the center.
Squirt- The action of a bowling ball as it hydroplanes past its break point.
Stacked Leverage- A layout where the pin and CG are the same distance from the bowler’s PAP.
Static Weights- Measurements of forces at work in systems that are at rest. Side, finger and top weights measured on a do-do scale.
Stroker- Someone who has a smooth swing and delivery without sudden acceleration.
Surface- The texture, both finish and hardness, of a bowling ball.
Tapered- Any hole in which the upper diameter of the hole is larger than the bottom.
Thumb Weight- An imbalance in a bowling ball which effectively makes the half of the ball containing the thumb heavier than the half containing the fingers, separated by the midline.
Track- Area of the bowling ball that makes contact with the lane surface during its path down the lane. Due to revolving motion, this area is usually in the form of a ring or rings around the ball.
Track Flare- The result of the migration of a bowling ball from the bowler’s axis of rotation to the ball’s preferred spin axis.
Track Flare Management- The regulation of the position of the flare intersections and thus the amount of flare.
Traction- The power, similar to tires on pavement, to grip or hold to a surface while moving without slipping.
Vertical Axis Line/Midplane- A line perpendicular to the midline that passes through the bowler’s positive axis point, and the negative axis point when extended completely around the ball; separates the top of the ball from the bottom of the ball on the bowler’s axis of rotation.
Vertical Axis Measurement- The perpendicular measurement from the midline to the bowler’s PAP.
Weight Block- Traditionally, the dense part of material found in the interior of a bowling ball designed to help create ball reaction.
Weight Hole- See "balance hole."
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