1. The magical word bestowed unto the wizard Shazam's champions, including Captain Marvel and Black Adam, that grants them "the wisdom of Solomon, the strength of Hercules, the stamina of Atlas, the power of Zeus, the courage of Achilles, and the speed of Mercury". The word is an anagram of the six legends that the champion's powers are said to be composed of.
EX. Did you know that, in 2012, DC made the "brilliant" decision to officially rebrand Captain Marvel as "Shazam" because, for literally decades, people though the character's name was his mentor/catchphrase/title of his comic book?
Personally, I think it's pretty lame. Captain Marvel is a cheesy name, but so is the hero. He is more of a boyscout than Superman. Renaming him "SHAZAM!" to appease the idiots would be like renaming Link to "Zelda" since so many people make that mistake.
Fun Fact: Elvis was a big comic book fan and actually based his costumes (the cape, hair, etc.) on his favorite hero, Captain Marvel Jr.