What are the reserved words for Esri's file geodatabase?

Answer

Certain words such as SELECT, DELETE, or UPDATE are reserved and should not be used for identifiers such as table, feature class and column names. Attempting to use a reserved word as a table name will return an error that the table (or feature class) name is invalid. Using a reserved word as a column name will return an error indicating that the column name is invalid. Copy/Paste from a data source where the word is not reserved will add a "_" to the end of any table or column name that is reserved within the file geodatabase.

Reserved words within a file geodatabase: