While the word "Satan" appears in many translations of the Old and New Testament, it is much more common in the N.T., with only a few mentions in the O.T. The word "Devil" seems almost exclusively used in the N.T., at least in the few versions I checked. This may have something to do with the word origin, Satan v Devil. But it says something more about the entity either word represents, the fact that in spite of its larger volume, the O.T. mentions Satan (the adversary) by name very few times, with the exception of the book of Job. (1 Chronicles 21:1;Job Chaps. 1 and 2; Zechariah 3:1,2)
It seems to me that, considering the numerous writers of the O.T., Satan was not an important entity, having to explain what the Israelites did as a nation. There's obviously more emphasis to Satan in the N.T. This struck me while reading about the influence of Zoroastrianism on Jewish beliefs (monotheism, the devil, dualism [soul], heaven and hell), that the concept of the evil one does not permeate the O.T. In a way, neither does the idea of dualism or hell in the Hebraic writings.
Nevertheless, it goes to show that monotheism was not an original construct for the Jews since Zoroastrianism can date as far back as 2,000 years BCE. Does anyone else have some insight into this?