Chambers 20th Century Dictionary(0.00 / 0 votes)Rate this definition: Sibilance. sibâ²i-lans, n. a hissing soundâalso Sibâ²ilancy.âadj. Sibâ²ilant, making a hissing sound.ân. a sibilant letter, as s and z.âv.t. Sibâ²ilÄte, to pronounce with a hissing sound.ân. SibilÄâ²tion, a hissing sound.âadjs.
Definition: A delta wave is a type of high amplitude brain wave found in humans. Delta waves have a frequency from one to four hertz and are measured using an electroencephalogram (EEG). These brain waves are thought to emerge from the thalamus and are generally associated with slow-wave sleep (during stages three and four of the stages of sleep.
coupled rhythm heart beats occurring in pairs, the second beat of the pair usually being a ventricular premature beat. delta rhythm. 1. electroencephalographic waves having a frequency below 3Â½ per second, typical in deep sleep, in infancy, and in serious brain disorders. See also electroencephalography. 2. delta waves.. junctional rhythm. nyctohemeral rhythm a day and night rhythm. pendulum rhythm alternation in the rhythm of the heart sounds in which the diastolic sound is equal in time, character, and loudness to the systolic sound, the beat of the heart resembling the tick of a watch.