High Quality Content by WIKIPEDIA articles! In physics, the wavelength of a sinusoidal wave is the spatial period of the wave ? the distance over which the wave's shape repeats. IT is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. WAvelength is commonly designated by the Greek letter lambda (?).