noun
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
• Hypernyms: ↑brainwave, ↑brain wave, ↑cortical potential
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noun or theta wave or theta : a relatively high amplitude brain wave pattern between approximately 4 and 9 hertz that is characteristic especially of the hippocampus but occurs in many regions of the brain including the cortex
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Physiol.
a pattern of brain waves having a regular frequency of 4 to 7 cycles per second as recorded by an electroencephalograph, observed during various states of light sleep or arousal.
[1945-50]
Useful english dictionary. 2012.