The full list is at https://learn.microsoft.com/sql/relational-databases/errors-events/database-engine-events-and-errors. To look up any error on the server itself:

SELECT message_id, severity, is_event_logged, text
FROM sys.messages
WHERE language_id = 1033
  AND message_id = 1222;

• Errors 0 to 999
• Errors 1,000 to 1,999
• Errors 2,000 to 2,999
• Errors 3,000 to 3,999
• Errors 4,000 to 4,999
• Errors 5,000 to 5,999
• Errors 6,000 to 6,999
• Errors 7,000 to 7,999
• Errors 8,000 to 8,999
• Errors 9,000 to 9,999
• Errors 10,000 to 10,999
• Errors 11,000 to 12,999
• Errors 13,000 to 13,999
• Errors 14,000 to 14,999
• Errors 15,000 to 15,999
• Errors 16,000 to 17,999
• Errors 18,000 to 18,999
• Errors 19,000 to 20,999
• Errors 21,000 to 21,999
• Errors 22,000 to 22,999
• Errors 23,000 to 25,999
• Errors 26,000 to 27,999
• Errors 28,000 to 30,999
• Errors 31,000 to 41,399
• Errors 41,400 to 49,999

From my SQL Server DBA handbook.