tetrachord

noun

tet·​ra·​chord ˈte-trə-ˌkȯrd 

: a diatonic series of four tones with an interval of a perfect fourth between the first and last

Word History

Etymology

Greek tetrachordon, from neuter of tetrachordos of four strings, from tetra- + chordē string — more at yarn

First Known Use

1603, in the meaning defined above

Kids Definition

tetrachord

noun

tet·​ra·​chord ˈte-trə-ˌkȯ(ə)rd 

: a series of four tones : half an octave