A noun "mackerel" represents certain smaller edible fish, primarily true mackerel and spanish mackerel in the family scombridae, often speckled, typically scomber scombrus in the british isles.

A true mackerel, any fish of tribe Scombrini (Scomber spp., Rastrelliger spp.)

Certain other similar small fish in families Carangidae, Gempylidae, and Hexagrammidae.