Cartoon by Dave Granlund published on 10 April 2009
A thug is a term applied to cruel or vicious robbers or murderers. The origin of the word dates back to the 19th century and comes from the Hindi word thag, literally meaning a rogue or a cheat.
The verb to prowl means to move quietly around in an area with the intention of doing something bad. The word also exists as a noun and is often found in the expression on the prowl. For example, Somali pirates are on the prowl around the Horn of Africa looking for ships and boats to attack.