Original: In the diatonic scale , and the other standard heptatonic scales of Western music , there are 7 notes ; if one counts both ends ( see Fencepost error ) there are 8 notes , hence the name '' octave '' , from the Latin octavus , from octo ( meaning '' eight '' ) .
Simplified: It is called an ` octave ' because there are eight notes in a scale ( ` octo ' is Latin for ` eight ' ) .