| Term | Definition |
| Wave | A disturbance that transfers energy from place to place |
| Energy | The ability to work |
| Medium | Material through which a wave travels |
| Mechanical wave | A wave that requires a medium through which to travel |
| Vibration | A repeated back-and-forth or up-and-down motion |
| Transverse wave | A wave that moves the medium in a direction perpendicular to the direction in which the wave travels |
| Crest | The highest part of a transverse wave |
| Trough | The lowest part of a transverse wave |
| Longitudinal wave | A wave that moves the medium parallel to the direction in which the wave travels |
| Compression | The part of a longitudinal wave where the particles of the medium are close together |
| Rarefaction | The part of a longitudinal wave where the particles of the medium are far apart |
| Surface wave | A wave that occurs at the surface between two mediums |
| Amplitude | The maximum distance the particles of a medium move away from their rest positions as a wave passes through the medium |
| Wavelength | The distance between two corresponding parts of a wave |
| Frequency | The number of complete waves that pass a given point in a certain amount of time |
| Hertz (Hz) | Unit of measurement for frequency |
| Reflection | The bouncing back of a wave when it hits a surface through which it cannot pass |
| Angle of incidence | The angle between an incoming wave and an imaginary line drawn perpendicular to the surface of the new medium |
| Angle of reflection | The angle between a reflected wave and an imaginary line drawn perpendicular to the surface of the new medium |
| Refraction | The bending of waves as they enter a different medium |
| Diffraction | The bending of waves around a barrier |
| Interference | The interaction between waves that meet |
| Constructive Interference | The interference that occurs when two waves combine to make a wave with a larger amplitude |
| Destructive Interference | The interference that occurs when two waves combine to make a wave with a smaller amplitude |
| Standing wave | A wave that appears to stand in one place, even though it is really two waves interfering as they pass through each other |
| Node | A point of zero amplitude on a standing wave |
| Antinode | A point of maximum amplitude on a standing wave |
| Resonance | The increase in the amplitude of vibration that occurs when external vibrations match the object’s natural frequency |
| Seismic wave | A wave produced by an earthquake |
| Primary wave | A longitudinal seismic wave |
| Secondary wave | A transverse seismic wave |
| Tsunami | Surface wave on the ocean caused by an underwater earthquake |
| Seismograph | Instrument used to detect and measure earthquakes |