ring assembly

https://doi.org/10.1351/goldbook.R05393
Two or more cyclic systems (single rings or fused systems) which are directly joined to each other by double or single bonds are named ring assemblies when the number of such direct ring junctions is one less than the number of cyclic systems involved. Examples:
R05393.png
Source:
Blue Book, p. 42 [Terms] [Book]