angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.
application: A particular use or function of something.
concentration: (in chemistry) A measurement of how much of one substance has been dissolved into another.
dissolve: To turn a solid into a liquid and disperse it into that starting liquid. (For instance, sugar or salt crystals, which are solids, will dissolve into water. Now the crystals are gone and the solution is a fully dispersed mix of the liquid form of the sugar or salt in water.)
equation: In mathematics, the statement that two quantities are equal. In geometry, equations are often used to determine the shape of a curve or surface.
football field: The field on which athletes play American football. Owing to its size and familiarity, many people use this field as a measure of how big something is. A regulation field (including its end zones) runs 360 feet (almost 110 meters) long and 160 feet (almost 49 meters) wide.
gelatin: A substance made from animal collagen, usually bones and cow or pig hides. It starts out as a pale colored, tasteless powder. It contains proteins and amino acids. It can make jiggly desserts (like those known as Jell-O). But this substance also is used in yogurt, soups, candies and more. It can even be used as the basis of the clear capsules used to hold single-serving amounts of dry medicines.
glass: A hard, brittle substance made from silica, a mineral found in sand. Glass usually is transparent and fairly inert (chemically nonreactive). Aquatic organisms called diatoms build their shells of it.
incidence: The rate or frequency at which something (usually undesirable) occurs. It might, for instance, be used to refer to how often new cancer cases emerge in a population of people or the rate of at which hurricanes develop each year over some part of the world’s oceans.
index of refraction: A measure of how light travels through a material. Scientists use the index to calculate how much light’s path will be bent as it moves from one medium to another.
lens: (in physics) A transparent material that can either focus or spread out parallel rays of light as they pass through it. (in optics) A curved piece of transparent material (such as glass) that bends incoming light in such a way as to focus it at a particular point in space. Or something, such as gravity, that can mimic some of the light bending attributes of a physical lens. (in social issues) An attitude or perspective that helps bring broad issues into focus.
liquid: A material that flows freely but keeps a constant volume, like water or oil.
mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.
optical: An adjective that refers to light or vision.
optics: Having to do with vision or what can be seen.
orientation: (v. orient) The deliberate arrangement of your position (of that of something else) relative to the cardinal directions (north south, east or west), to the ordinal directions (northeast, southeast, southwest or northwest) or to some landmark (such as the horizon, a particular street corner or a statue).
perpendicular: An adjective that describes two things that are situated approximately 90 degrees to each other. In the letter “T,” the top line of the letter is perpendicular to the bottom line.
physics: The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study that emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in such areas is known as a physicist.
plastic: Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation. (adj.) A material that is able to adapt by changing shape or possibly even changing its function.
ray: (in mathematics) A line that has a defined endpoint on one side, but the other side continues on forever. refraction: The change in direction of light (or any other wave) as it passes through some material. For example, the path of light leaving water and entering air will bend, making partially submerged objects to appear to bend at the water’s surface.
salt: A compound made by combining an acid with a base (in a reaction that also creates water). The ocean contains many different salts — collectively called “sea salt.” Common table salt is a made of sodium and chlorine.
solution: A liquid in which one chemical has been dissolved into another.
solvent: A material (usually a liquid) used to dissolve some other material into a solution.
speed of light: A constant often used in physics, corresponding to 1.08 billion kilometers (671 million miles) per hour.
square: (in geometry) A rectangle with four sides of equal length. (In mathematics) A number multiplied by itself, or the verb meaning to multiply a number by itself. The square of 2 is 4; the square of 10 is 100.
theory: (in science) A description of some aspect of the natural world based on extensive observations, tests and reason. A theory can also be a way of organizing a broad body of knowledge that applies in a broad range of circumstances to explain what will happen. Unlike the common definition of theory, a theory in science is not just a hunch. Ideas or conclusions that are based on a theory — and not yet on firm data or observations — are referred to as theoretical. Scientists who use mathematics and/or existing data to project what might happen in new situations are known as theorists.
thrust: A force that makes an object move forward.
tool: An object that a person or other animal makes or obtains and then uses to carry out some purpose such as reaching food, defending itself or grooming.
trajectory: The path taken by a projectile moving through space and time, or the direction that a trend is taking over time.
variable: (in mathematics) A letter used in a mathematical expression that may take on different values. (in experiments) A factor that can be changed, especially one allowed to change in a scientific experiment. For instance, when researchers measure how much insecticide it might take to kill a fly, they might change the dose or the age at which the insect is exposed. Both the dose and age would be variables in this experiment.
verify: (n. verification) To demonstrate or confirm in some way that a particular claim or suspicion is true.
vertical: A term for the direction of a line or plane that runs up and down, as the vertical post for a streetlight does. It’s the opposite of horizontal, which would run parallel to the ground.
wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.