In Fantastic Beasts and Where to Find them, we learn about the Magical Congress of the United States of America (shortened MACUSA).
Indeed they abbreviate it to this acronym in common speech (pronounced "Ma-koo-za"), but is heavily implied to be an official abbreviation, much like SWAT (Special Weapons and Tactics) and Navy SEALs (Sea Air Land), both in and out of universe.
Where is the first A in MACUSA coming from (i.e. obviously from Magical, but how come it gets away with using the letter A when it isn't an initial for one of the words that it's abbreviating)? Is there an official reason or out-of-universe explanation?