7b9 chords
A dominant seventh with a flattened ninth stacked on top, tense and dramatic. It shows up constantly in jazz and in flamenco-adjacent harmony, and it resolves with even more urgency than a plain dominant seventh does.
Other chord types
MajorMinorDiminishedAugmentedSuspended 2ndSuspended 4thDominant 7thMajor 7thMinor 7thMajor 6thMinor 6thMinor Major 7thDiminished 7thHalf-Diminished 7thAugmented 7thAdd9Dominant 9thMajor 9thMinor 9th6/9Dominant 11thMinor 11thDominant 13thMajor 13thMinor 13th7sus47b57#9Dominant 7#11Minor 6/99sus4Power Chord (5)Minor Add9Add117sus213sus4Minor Major 9thMajor 7#11Major 9#117b1313b913#117altAugmented Major 7thMinor 9b5Quartal (So What)