cumulative double bonds

https://doi.org/10.1351/goldbook.C01437
Those present in a chain in which at least three contiguous carbon atoms are joined by double bonds; non-cumulative double bonds comprise every other arrangement of two or more double bonds in a single structure. The generic name 'cumulene' is given to compounds containing three or more cumulative double bonds.
Source:
Blue Book, p. 20 [Terms] [Book]