Abbreviation for Year 2000. The Y2K abbreviation is now the buzz word for referencing all of the potential problems that lie ahead for big computer systems when they begin to have to deal with dates after the year 2000. The problem stems from the fact that many older systems were designed to accommodate only two-digit year codes. So a date might look like 8/13/98 as opposed to 8/13/1998. After the year 2000 the date might look like 8/13/00 and it is unknown how the software on many computer systems will interpret this date. There is currently an explosion of new companies whose sole offer is to evaluate complex computer systems for vulnerability to this problem and correct where necessary.