Wiktionary
n. (context trigonometry signal processing English) A waveform described by the sine function, possibly shifted by some phase.
WordNet
n. a wave whose waveform resembles a sine curve
Wikipedia
A sine wave or sinusoid is a mathematical curve that describes a smooth repetitive oscillation. It is named after the function sine, of which it is the graph. It occurs often in pure and applied mathematics, as well as physics, engineering, signal processing and many other fields. Its most basic form as a function of time (t) is:
y(t) = Asin(2πft + φ) = Asin(ωt + φ)
where:
 A = the amplitude, the peak deviation of the function from zero.
 f = the ordinary frequency, the number of oscillations (cycles) that occur each second of time.
 ω = 2πf, the angular frequency, the rate of change of the function argument in units of radians per second

φ = the phase, specifies (in radians) where in its cycle the oscillation is at t = 0.
 When φ is nonzero, the entire waveform appears to be shifted in time by the amount φ/ω seconds. A negative value represents a delay, and a positive value represents an advance.
The sine wave is important in physics because it retains its wave shape when added to another sine wave of the same frequency and arbitrary phase and magnitude. It is the only periodic waveform that has this property. This property leads to its importance in Fourier analysis and makes it acoustically unique.
Usage examples of "sine wave".
The horizon was undulating like a sine wave, and people and animals were mewling with fear all around him.
In order to practice flattening separate combinations of lines at once, I would watch my screen and see when different sine wave boxes would light up.
The cycle of madness on Earth was coming around again, caught in its inexorable sine wave, a sine wave more awful even than Maya's, and soon they would be back in the midst of one of those paroxysms, out of control, struggling to avoid obliteration.
The cycle of madness on Earth was coming around again, caught in its inexorable sine wave, a sine wave more awful even than Maya’.
He added a simple sine wave to itself, which had the effect of doubling the height of the peaks and troughs of the wave.
The pattern appears to be a sine wave, so we should go to the north of Germany.
He drew another sine wave over the first, yet the peaks of the second were where the valleys of the first one were, and vice versa.
Back to the real, with its blessed sense of newness, contingency, blind becoming, where she was free to experience each moment with surprise, and feel the ordinary rise and fall of her emotional sine wave, a roller coaster which though uncomfortable was at least movement.