AFCT key terms

A word that has the same or nearly the same meaning as another word, such as "begin" and "start". Word Knowledge questions often ask you to pick the answer closest in meaning to the given word.

A word that means the opposite of another word, such as "expand" and "shrink". Recognizing opposites helps eliminate wrong answer choices quickly.

A hint about a word's meaning found in the surrounding sentence, such as a contrast word or an example. Using nearby words often reveals an unfamiliar term's sense without a dictionary.

The feeling or attitude a word suggests beyond its literal meaning, such as "thrifty" versus "stingy". Two words with similar definitions can carry very different emotional shades.

The exact, dictionary meaning of a word apart from any emotional suggestion. Distinguishing it from connotation helps you choose the most precise answer.

The central point a paragraph is built around, usually stated or strongly implied in one sentence. Everything else in the passage supports, explains, or illustrates it.

A sentence, often first in a paragraph, that announces what the paragraph will be about. It acts as a signpost for the writer's main point.

A fact, example, or reason that backs up the main idea of a passage. Details answer who, what, when, where, or why about the central claim.

A conclusion drawn from evidence in the text rather than stated outright. You combine stated facts with logic to reach a reasonable but unstated meaning.

The writer's attitude toward the subject, revealed through word choice and phrasing, such as humorous, bitter, or objective. Tone differs from the reader's own reaction.

A comparison of two quantities by division, often written as a fraction or with a colon, such as 3:4. Ratios let you scale amounts up or down proportionally.

An equation stating that two ratios are equal, such as 2/3 = 4/6. Solving a proportion means finding the unknown value that keeps both sides balanced.

A ratio that compares quantities with different units, such as miles per hour or dollars per pound. Rates are often used in word problems about speed, pay, or work.

A rate expressed per single unit of the second quantity, such as cost per one item. Finding the unit rate makes comparisons between different offers straightforward.

A part expressed as a fraction of one hundred, where 25% means 25 out of 100. To use it in arithmetic, convert it to a decimal or fraction first.

The amount something grows, divided by the original amount, then written as a percent. Always divide by the starting value, not the new one.

The sum of a set of values divided by how many values there are. It gives a single number representing the center of the data.

The middle value in a list of numbers arranged from least to greatest; with an even count, it is the mean of the two middle values. Unlike the average, it is not pulled by extreme values.

A letter or symbol standing for an unknown or changing number, such as x in 3x + 2 = 11. Solving for it means isolating it on one side of the equation.

A mathematical statement that two expressions are equal, joined by an equals sign. Whatever you do to one side must also be done to the other.

A statement comparing two expressions that are not necessarily equal, using symbols like <, >, ≤, or ≥. Solving one works like an equation, except multiplying or dividing by a negative flips the sign.

A small raised number showing how many times the base is multiplied by itself, as in 2³ = 2 × 2 × 2. It is not the same as multiplying the base by the exponent.

A number that, when multiplied by itself, gives the original value; the square root of 49 is 7. Every positive number has two square roots, one positive and one negative.

The total distance around the outside of a flat shape, found by adding the lengths of all its sides. It is measured in linear units such as inches or meters.

The amount of surface a flat shape covers, measured in square units. For a rectangle it equals length times width.

The distance around a circle, calculated as pi times the diameter. It is the circular counterpart of perimeter.

The longest side of a right triangle, lying opposite the right angle. Its length squared equals the sum of the squares of the other two sides.

How much mass is packed into a given volume of a substance, often written as mass divided by volume. Denser objects sink in fluids less dense than themselves.

The amount of matter in an object, which stays the same regardless of location. It differs from weight, which changes with gravity.

The amount of space an object or substance occupies, measured in cubic units or liters. For a rectangular box it is length times width times height.

The process by which green plants use sunlight, water, and carbon dioxide to make sugar and release oxygen. Chlorophyll in leaves captures the light energy that drives it.

The change of a liquid into a gas, which happens at the surface and speeds up with heat. It is part of the water cycle that returns moisture to the air.

The change of a gas into a liquid as it cools, such as water droplets forming on a cold glass. It is the reverse of evaporation.

The electrical pressure that pushes current through a circuit, measured in volts. A higher voltage can drive more current through the same resistance.

The flow of electric charge through a conductor, measured in amperes. It moves only when a complete path exists from the source and back.

The opposition to the flow of electric current, measured in ohms. Higher resistance reduces current for a given voltage, and it produces heat as energy is lost.

A circuit in which components are connected in a single path, so the same current flows through each. If one part breaks, the whole circuit stops working.

A circuit in which components are connected on separate branches, so each gets the full source voltage. If one branch fails, the others keep operating.

A twisting force that tends to rotate an object, equal to force times the distance from the pivot. A longer wrench gives more torque for the same push.

The mechanical advantage gained by using a lever, allowing a small force to move a larger load. It depends on the distances from the fulcrum to the effort and the load.

The factor by which a machine multiplies the force applied to it. A machine with an advantage of 4 lets a small effort lift a load four times heavier.

The comparison of the number of teeth on two meshing gears, which sets how speed and torque trade off. A small gear driving a large one increases torque but slows rotation.

A force that squeezes or shortens a material, as when a piston presses gas in a cylinder. It is the opposite of tension, which pulls material apart.

The sequence of intake, compression, power, and exhaust strokes that a typical gasoline engine repeats. Each stroke moves the piston once up or down the cylinder.

A fluid that circulates through an engine to carry away excess heat and keep it from overheating. It absorbs heat at the engine and releases it through the radiator.

A substance such as oil that reduces friction between moving parts and carries away some heat. Regular changes keep an engine from wearing out prematurely.

The fixed pivot point on which a lever turns. Moving the load or effort farther from it changes how much force is needed to lift.