Wiktionary
ser.
n. 1 (context legal English) (abbreviation of serial English) 2 (context legal English) (abbreviation of series English)
Usage examples of "ser.".
White highways for another year, ser. I must warn you that if anyone tampers with the medallion, you will need another.
I must have bumped into Dett, ser. We all got tangled in the bruggage.