Specifically, the word comes from the Tupi word "ja'biru", which refers to the Jabiru bird (Jabiru mycteria).
The Tupi language is known for its rich vocabulary and its use of onomatopoeia, and the word "ja'biru" likely imitates the bird's call.
Over time, the word "jabiru" was adopted into Portuguese and then spread to other languages, including English. It's now the common name for the large, stork-like bird found in South America.