Given its size, being named after the river turned out to be appropriate. Yet it has pulled an "abracadabra" of sorts, but that name would have been too similar to another large entity: "Alibaba".
"Amazon.com was very nearly called "Cadabra," as in "abracadabra." Founder Jeff Bezos rapidly re-conceptualized the name when his lawyer misheard the word as "cadaver."
Bezos instead named the business after the river reportedly for two reasons. One, to suggest scale (Amazon.com launched with the tagline "Earth's biggest book store") and two, back then website listings were often alphabetical."