Amazon River Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. a major South American river; arises in the Andes and flows eastward into the South Atlantic; the world's 2nd longest river 4000 miles Example Sentence We boated down the Amazon River. Synonyms South American river; 2nd longest river; river Antonyms mountain Hear It! Say It! Write It! Amazon River Switch to cursive Start Share with your friends: