IRC /I-R-C/ n. [Internet Relay Chat] A worldwide "party line" network
   that allows one to converse with others in real time. IRC is structured
   as a network of Internet servers, each of which accepts connections from
   client programs, one per user. The IRC community and the {Usenet} and
   {MUD} communities overlap to some extent, including both hackers and
   regular folks who have discovered the wonders of computer networks. Some
   Usenet jargon has been adopted on IRC, as have some conventions such as
   {emoticon}s. There is also a vigorous native jargon, represented in this
   lexicon by entries marked `[IRC]'. See also {talk mode}.


Source: The Jargon File

IRC
     Internet Relay Chat [protocol] (RFC 1459, Internet)
     
     
Source: Virtual Entity of Relevant Acronyms

IRC
     InformationsRessourcen Controlling (IM)
     
     
Source: Virtual Entity of Relevant Acronyms