Definition of "theta" [the•ta]

• The eighth letter of the Greek alphabet. See Table at alphabet. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "If you are reading something, language areas oscillate in theta frequency allowing high-gamma-related neural activity in individual neurons to transmit information, said Knight."
• "This temperature Professor Flory named the theta temperature."
• "The stimulation also increased so-called theta waves in the hippocampus, a low-frequency global rhythm that seems to coordinate the firing of neurons and aid memory."