argot

Short definition from Wiktionary

Noun

1. 1
   A secret language or conventional slang peculiar to thieves, tramps and vagabonds.
2. 2
   The specialized informal vocabulary and terminology used between people with special skill in a field, such as between doctors, mathematicians or hackers.
3. 3
   A strongly marked style of speaking.
4. 4
   An inhabitant or resident of Argos.