The Cruizer class was an 18-gun class of brig-sloops of the Royal Navy. Brig-sloops were the same as ship-sloops except for their rigging. A ship-sloop was rigged with three masts whereas a brig-sloop was rigged as a brig with only a fore mast and a main mast.

In the 18th century and most of the 19th, a sloop-of-war in the Royal Navy was a warship with a single gun deck that carried up to eighteen guns. The rating system covered all vessels with 20 guns and above; thus, the term sloop-of-war encompassed all the unrated combat vessels, including the very small gun-brigs and cutters. In technical terms, even the more specialised bomb vessels and fireships were classed as sloops-of-war, and in practice these were employed in the sloop role when not carrying out their specialised functions.