What is the word for a group of genes inherited together?

I believe you are referring to operon?

In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splicing to create monocistronic mRNAs that are translated separately, i.e. several strands of mRNA that each encode a single gene product.

There is also a term called supergene which is in a way a less strict grouping, suggesting close genetic linkage and possible functional relationship.