Elektra chord
The Elektra chord is a "complexly dissonant signature-chord" and motivic elaboration used by composer Richard Strauss to represent the title character of his opera Elektra that is a "bitonal synthesis of E major and C-sharp major" and may be regarded as a polychord related to conventional chords with added thirds, in this case an eleventh chord. It is enharmonically equivalent to a 79 chord, D–F–A–C–E, and a 69 chord, E–G–B-C-F.
In the opera, the chord—Elektra's "harmonic signature"—is treated various ways betraying "both tonal and bitonal leanings... a dominant over a nonharmonic bass." It is associated as well with its seven-note complement which may be arranged as a dominant thirteenth while other characters are represented by other motives or chords, such as Klytämnestra's contrasting harmony. The Elektra chord's complement appears at important points and the two chords form a 10-note pitch collection, lacking D and A, which forms one of Elektra's "distinctive 'voices'."