(n) the normal brainwave in the encephalogram of a person in deep dreamless sleep; occurs with high voltage and low frequency (1 to 4 hertz), Syn. delta wave
(n) the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude, Syn. theta wave
[ひきなみ, hikinami] (n) (1) (See 寄せ波) backwash; rip current; undertow; (2) stern wave; (3) (See 押し波) drawback (of a tsunami, i.e. when a wave trough reaches land before a crest)