It means five sounds or tones in a row. You can also use pentaphone or pentaphonic.
Five-tone, it is usually used in music with a scale of five heights or tones. From Greek 960; 949; 957; 964; 949; (pente "five" ) 964; 959; 957; 959; 962; ( tones "tensed like a string, toned, strong" ) .