The Sanskrit word "श्रुति" (IAST: Śruti, IPA: [ɕɽʊt̪ɪ]) has multiple meanings depending on context. It means "hearing, listening", a call to "listen to a speech", any form of communication that is aggregate of sounds (news, report, rumor, noise, hearsay). The word is also found in ancient geometry texts of India, where it means "the diagonal of a tetragon or hypotenuse of a triangle", and is a synonym of karna. The word śruti is also found in ancient Indian music literature, where it means "a particular division of the octave, a quarter tone or interval" out of twenty-two enumerated major tones, minor tones, and semitones. In music, it refers the smallest measure of sound a human being can detect, and the set of twenty-two śruti and forty four half Shruti, stretching from about 250 Hz to 500 Hz, is called the Shruti octave.
In scholarly works on Hinduism, śruti refers to ancient Vedic texts from India. Monier-Williams traces the contextual history of this meaning of śruti as, "which has been heard or communicated from the beginning, sacred knowledge that was only heard and verbally transmitted from generation to generation, the Veda, from earliest Rishis (sages) in Vedic tradition. In scholarly literature, Śruti is also spelled as Shruti.