Source : Webster's Revised Unabridged Dictionary (1913)

American Protective Association \A*mer"i*can Pro*tect"ive
As*so`ci*a"tion\
   A secret organization in the United States, formed in Iowa in
   1887, ostensibly for the protection of American institutions
   by keeping Roman Catholics out of public office. Abbrev.
   commonly to A. P .A.