"delta wave." YourDictionary, n.d. Web. 19 September 2018. <http://www.yourdictionary.com/delta-wave>.
delta wave. (n.d.). Retrieved September 19th, 2018, from http://www.yourdictionary.com/delta-wave
An electrical oscillation occurring in the human brain at a frequency of less than about four hertz as recorded on an electroencephalogram, associated with a state of deep sleep or unconsciousness. Also called delta rhythm .