A four-letter synonym for Ireland is "Eire" - but this is not an abbreviation.
An four letter abbreviation for Connecticut is Conn.
The abbreviation used on CARS when people travel aborad is IRL for example.
The abbreviation for Saskatchewan Canada is SK
USPS
four letter word for facts: data (also info, but that's an abbreviation)
cork
IRE and IRL are both used as abbreviations for Ireland.
crts (abbreviation for cathode ray tubes)
The standard two letter abbreviation for the state of South Dakota is SD.
Norther Ireland
the abbreviation is T