dienes

https://doi.org/10.1351/goldbook.D01699
Compounds that contain two fixed double bonds (usually assumed to be between carbon atoms). Dienes in which the two double-bond units are linked by one single bond are termed conjugated, e.g. CH2=CH–CH=CH2 buta-1,3-diene. Dienes in which the double bonds are adjacent are called cumulative, e.g. CH3–CH=C=CH2 buta-1,2-diene. Those in which one or more of the unsaturated carbon atoms is replaced by a heteroatom may be called heterodienes.
See:
alkenes
,
allenes
,
cumulenes
,
diols
,
olefins
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1332 [Terms] [Paper]