I assumed the word was derived from "azul" but from the article, it's apparently derived from the Arabic الزليج (al-zillīj) and has no relation with "azul"
The arabic word for "azul" is أزرق (azraq) so they all look pretty adjacent.
interestingly, apparently "azul" also comes from the arabic "lāzuward"
This wikipedia article, the wiktionary entry for Portuguese, and the Spanish wiktionary entry all have different etymologies lmao.
As a Spanish speaker it seems really hard to believe it's not azul + -ejo. They're literally blue.
Portuguese here - many Portuguese words have origin from Arabic as Portugal has been conquered and occupied by "the Moors" in 8th~13th century. That's a long time! Alentejo, Aljezur, Algarve, and many of the cities in the Southern part of the country have have Arabic origins.