Science Vocabulary Words You Should Know

ACT Science is all about getting the maximum number of questions right in a relatively short period. Having a strong vocabulary helps a lot in improving your understanding of the questions and reducing the time it would take for you to understand the question. This article will help you improve your ACT score by compiling a list of commonly used words in the ACT Science vocabulary along with their meanings.

Remember that this word list is not a substitute for the concepts themselves. It serves as a summary of commonly used words with which you need to be familiar. However, if you do not understand a word or the associated concept, it is necessary that you study that concept from a recommended textbook.

A Few Tips to Help You Remember the Words and Concepts

Some students understandably have a hard time memorizing a given list of words or phrases. Here are a few tips which might help you if you feel like you’re getting stuck and are unable to remember the words or concepts:

Use flashcards as a tool for improving your learning.
Do not try to study and remember all of them at once. ACT Science vocabulary is not something you can read once and then remember. Break them down into sets of 10 – 20 words and then study them. Once you feel confident with one set, move onto the next set until you are done.
If you are unable to understand the underlying concept, try looking it up in your textbook or online. It is always easier to remember something you understand rather than simply memorizing it.
You can also use the list as a tool for a quick review before your ACT exam.

The 101 Words

Here is a list of words which have commonly been a part of the ACT Science vocabulary. However, keep in mind that this list is not exhaustive and would not contain all the possible words and concepts you would need to know.

Absolute zero: the lowest possible temperature. It is 0 Kelvin or approximately -273 degrees Celsius.
Abundant: something which is plentiful or exists in large quantities.
Acceleration: rate of change of velocity, often expressed in m/s².
Acid: a molecule capable of donating a positively-charged hydrogen ion, or capable of forming a covalent bond by donating an electron pair.
Adhere: to stick completely on a surface.
Aerobic respiration: the process of glucose breakdown in the body of an animal for supplying muscles with oxygen.
Altitude: the vertical distance between an object and the ground or sea level; any object on the ground or sea level is said to have 0 altitude.
Analyze: to examine something in detail (such as phenomena, the result of an experiment, data collected from a survey, etc.).
Anecdote: a story told by someone based on his/her past experiences.
Anticipate: to predict an event or a result based on current events or past experiences.
Assert: to state a fact or belief with authority and confidence; to make others believe in one’s authority.
Burgeon: for something to grow or increase rapidly.
Attribute: a feature or property which is regarded as a part of something or someone.
Characteristic: something which is commonly a feature or a quality of a person, place, or a thing.
Carbohydrate: an organic compound containing carbon, hydrogen, and oxygen at a ratio of 1:2:1. For example, sugars and starches are the main sources of energy for living beings.
Catalyst: a substance which speeds up a chemical reaction but does not change the outcomes of the reaction.
Chlorophyll: the green pigment present in plants which captures light energy for photosynthesis.
Coherent: logical and consistent with the preceding arguments, theories, or policies.
Correspond: to agree or correlate with; to communicate by exchanging messages.
Combustion: a high-temperature reaction involving a fuel and an oxidant (usually oxygen), commonly associated with the process of burning.
Compose: to be a part of or to make up something; to write or create a work of literature, art, science, etc.
Compressibility: a measure of the amount of effort it would take to reduce the volume of the matter by applying pressure. Lower compressibility would indicate more effort is required to reduce the volume.
Conduction and conductivity: conduction is the transmission of energy like heat or electricity. Conductivity is an attribute of a material specifying its efficiency in transferring that energy.
Conductor: a material which offers minimum resistance to the flow of heat or electricity.
Contour: the outline which represents the bounding shape of an object or form; to mold something into a specific shape.
Consecutive: something which is followed in an unbroken or continuous sequence.
Contradict: to assert the opposite or to deny the truth of a statement.
Correlate: to have a mutual relationship or connection between two or more things.
Critical: expressing harsh or disapproving comments or judgments about something; analyzing a work of science, literature, music, etc.; describing a situation or a problem which can be potentially disastrous.
Decelerate: to slow down, or to reduce the speed (or velocity) of a moving body.
Deposition: a substance that is naturally deposited somewhere.
Determine: to find the exact cause and explanation of an event, phenomena, result (in an experiment), etc.
Diffusion time: the amount of time it takes for molecules or atoms of a material to spread from an area of high concentration to an area of lower concentration.
Distinguish: to treat something or recognize it as different.
Dissoluble: something which can be dissolved into another liquid or aqueous solution.
Ecology: the field of science which is concerned with relationships between organisms and their environments.
Efficient: to be able to accomplish a task or a purpose without wasting resources (such as time, energy, money, etc.).
Electron: a fundamental part of an atom. It is negatively charged.
Emit: to discharge, generally used in the context of heat, light, radiation, etc.
Emerge: to become obvious, more prominent, or important.
Emulsion: a state where one liquid is suspended in another but the two liquids would not dissolve in one another.
Engage: to make someone or something involved in an event, conversation, or discussion; to participate or get involved in something; to keep someone’s interest.
Equilibrium: a state where all the constituents of a system (such as reactants in a chemical reaction) are in balance.
Erode or Erosion: the process of air or water flow removing soil, rock, or material from one location and transporting them to another location.
Evolve: to develop something gradually; to develop something from a simpler form to more complex forms.
Exhibit: to make property or a skill visible or apparent.
Fermentation: the chemical process of breaking something down into simpler substances. For example, when sugar is fermented into alcohol.
Friction: a force acting between two solid surfaces where the relative motion of the surfaces is resisted.
Fuse: (verb) to join different objects together; (noun) a safety device used in electrical equipment which breaks the circuit in case more current than desired is drawn into the circuit.
Gauge: (verb) to estimate or measure a property (such as volume, amount, etc.); (noun) a device which measures a certain property of something.
Given: information which is specified or stated.
Habitat: an area where an organism naturally lives in the ecosystem.
Herbivore: an animal that survives by exclusively eating plants.
Humidity: the measurement representing the amount of water vapor present in the air.
Hypothesis: a tentative theory which has not been verified or proven, but tries to explain certain facts or phenomena.
Imminent: an event which is close to happening; something which is about to happen in a short period.
Incendiary: something which causes conflicting arguments; a device which is designed to cause and propagate fires.
Incremental: a quantity which is gradually increasing with discrete additions regularly.
Indigenous: something which naturally exists in a certain area or is native to that area.
Infer: to deduce a conclusion not explicitly written in the given evidence and information.
Infrared radiation: Electromagnetic waves with wavelengths longer than those of visible light (0.7 microns).
Impervious: something which is immune to any change from another thing (specific or in general).
Insoluble: something which cannot be dissolved into another liquid or aqueous solution.
Insulator: the opposite of conductor, a substance which resists the transfer of heat or electricity through it.
Interval: a deterministic period between two activities or instants.
Ion: a molecule or an atom which has a positive or negative charge due to losing or gaining one or more electrons
Kinetic energy: the energy of the motion of an object.
Latter: the second statement stated of the two previous statements.
Mass: a measure determined by the amount of matter or energy present in a body, it is the measure of a body’s resistance to acceleration.
Neutron: a fundamental part of an atom which has no charge.
Notion: a belief about something, an impulse, or desire.
Obsolete: something which is no longer of any use, or has a viable replacement which is easier to obtain or function.
Organic matter: carbon-based compounds found within natural environments and beings.
Osmosis: the process of liquid moving through a semipermeable membrane from a less concentrated solution to a more concentrated solution.
Omit: to exclude some information intentionally or forgetfully; to fail or neglect to do something.
Precipitation: phenomena of any form of water falling to the ground (in the form of rain, mist, snow, etc.).
Parasite: an organism which uses another organism as a host and feeds off the host for survival.
pH: a scale from 1-14 which specifies the concentration of hydrogen ions in an aqueous solution. It represents the alkalinity or acidity of that solution. A pH value of 7 is neutral, lower is acidic, and higher is alkaline.
Photosynthesis: a process used by plants to convert carbon dioxide and water into glucose, using energy from sunlight.
Precede: an event which occurs before another event in time; something which comes before another thing regarding their positions.
Principle: something which forms the foundation of a system or behavior.
Proficient: to be well versed and skilled in using a tool or thing.
Prolong: to increase the duration or the physical space of an event or object.
Proportionality: the relationship between two distinct quantities or amounts. In “directly proportional” quantities, an increase of one quantity causes the increase of the other quantity. In “indirectly proportional” quantities, increase of one quantity causes the decrease of the other quantity.
Protein: a compound made up of amino acids which plays several roles in forming the structural components of the body (such as muscles, hair, etc.) within an organism.
Proton: a fundamental part of the atom which is positively charged.
Radioactive decay: a naturally occurring process by which an atom spontaneously decays into another atom of a different element.
Redundant: information which is no longer needed or is of use, usually because it has been stated or deduced earlier.
Relevant: information which is related or appropriate to the subject or holds some value or interest to the subject being discussed.
Residual: remaining parts after an activity has been done to an object, or something which was left over.
Solution: a mixture of two or more substances which is homogeneous (has a uniform mixture and composition).
Specific gravity: the ratio of the weight of one substance to the weight of a different substance.
Starch: a complex carbohydrate which forms the energy supply within many vegetables.
Substrate: a substance which is acted upon by an enzyme; a layer which is underneath another layer.
Trial: testing the performance or result of an experiment.
Uniform: something which always shows the same form or manner without variation.
Variable: a factor which is meant to be changed in an experiment to determine the effects it has on the experiment.
Vapor: liquid in gaseous state.
Velocity: the speed and direction of an object’s motion.
Viscosity: the tendency of a liquid to resist flow. More viscous liquids flow more slowly than less viscous ones.
Wavelength: the distance between two successive crests of a wave, such as a sound wave or electromagnetic wave.