**average**: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
**axis**: (in mathematics) The line to the side or bottom of a graph. It is labeled to explain the graph’s meaning and the units of measurement.
**compression**: Pressing on one or more sides of something in order to reduce its volume.
**develop**: To emerge or to make come into being, either naturally or through human intervention, such as by manufacturing.
**diameter**: The length of a straight line that runs through the center of a circle or spherical object, starting at the edge on one side and ending at the edge on the far side.
**disk**: A round, flat and usually fairly thin object.
**egg**: A reproductive cell that contains half of the genetic information necessary to form a complete organism. In humans and in many other animals, ovaries produce eggs. When an egg fuses with a sperm, they combine to produce a new cell, called a zygote. This is the first step in the development of a new organism."
**engineering**: The field of research that uses math and science to solve practical problems. Someone who works in this field is known as an engineer.
**force**: Some outside influence that can change the motion of an object, hold objects close to one another, or produce motion or stress in a stationary object.
**information**: (as opposed to data) Facts provided or trends learned about something or someone, often as a result of studying data.
**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.
**motor**: A device that converts electricity into mechanical motion.
**online**: (n.) On the internet. (adj.) A term for what can be found or accessed on the internet.
**parallel**: An adjective that describes two things that are side by side and have the same distance between their parts. In the word “all,” the final two letters are parallel lines. Or two things, events or processes that have much in common if compared side by side.
**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.
**shell**: The normally hard, protective outer covering of something. It could cover a mollusk or crustacean (such as a mussel or crab), a bird’s egg or some other relatively soft tissue that needs protection (such as a tree nut or peanut). (in munitions) An explosive bullet, bomb, grenade or other projectile. (in physics) The orbital paths that electrons take around the nucleus of an atom.
**standard deviation**: (in statistics) The amount that each a set of data varies from the mean.
**strain**: (in physics) The forces or stresses that seek to twist or otherwise deform a rigid or semi-rigid object.
**structural engineer**: An individual who uses science to determine the strength or vulnerabilities of a building, bridge or other structure.
**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.
**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.