incumbent noun [C]. âº the âperson who has or had a âparticular âofficial âposition: the first/last/âprevious incumbent The âpresent incumbent (of the âpost) is âdue to âretire next âmonth. (Definition of incumbent from the Cambridge Advanced Learners Dictionary & Thesaurus Â© Cambridge University Press). See all translations.
In music, a linear progression (Auskomponierungszug or Zug, abbreviated: Zg. ) is a passing note elaboration involving stepwise melodic motion in one direction between two harmonic tones.  The compositional unfolding of a specific interval, one of the intervals of the chord of nature.
Horizontal Undulatory Progression or Lateral Progression for short. This method of movement is accomplished by the snake lashing it's body back and forth causing lateral waves that force longitudinal motion. To put it another way: They go forward by moving sideways. So imagine a person jumping in diagonal leaps.