What does the term Wavelength mean?

Hint:Wavelength is defined as distance between two successive crests or troughs of a wave. Crest is the highest point of a wave whereas trough is the lowest point of a wave.As the SI unit of wavelength is metre so it is basically distance measured between two points. Wavelength is denoted by lambda ($\lambda $).

Complete answer:
Wavelength is the distance from one crest to another or from one trough to another. The SI unit of wavelength is metre. CGS unit is centimetre. It is also measured in nanometres or micrometres. There are many electromagnetic radiations like Light waves, Infrared waves, Radio waves which make characteristic patterns as they travel through space. Wavelength can also be described by a formula:
$\lambda =\frac{\nu }{f}$
where $\nu $ means speed of wave, $f$ denotes frequency of wave and $\lambda $ denotes wavelength.

Amplitude is the maximum displacement from the central position to its extreme position(highest point of a crest or lowest point of a trough) and frequency is the number of waves passing through a point in one second. Wavelength of light is different for every colour.

Red colour has the longest wavelength whereas Violet colour has the shortest wavelength. Frequency is inversely proportional to wavelength. Thus, Red colour has lowest frequency and Violet colour has highest frequency. As, Red colour has the longest wavelength, red light deviates the least. Therefore, Red light is used in traffic signals and emergency signals.

Note:Electromagnetic waves have a very important role in our daily lives as they are used in cooking, satellite signals, communication, remote controls, gadgets, treatment of cancer etc.Wavelength is defined as the property of a wave in which the distance between the identical points between the two successive waves are calculated.