cadency
/ˈkeɪdənsɪ/noun
mass noun
- chiefly Heraldry the status of a younger branch of a family【主纹章】（家族的）非长子地位。
词源
early 17th cent. （in the sense 'rhythm or metrical beat'）： based on Latin cadent- 'falling', from the verb cadere. The current sense is apparently by association with CADET.