Sr is a written abbreviation for (書面縮略=) Senior, and is written after a man's name. It is used in order to distinguish a man from his son when they both have the same name.
例句
...Donald Cunningham, Sr.老唐納德·卡寧厄姆
英英詞典釋義
Noun
1. the unit of solid angle adopted under the Systeme International d'Unites