Watchers:-
The Watchers story in Enoch is derived from Genesis chapter 6. Verses 1-4 describe the “Origin of the Nephilim” and mention the “Sons of God” who beget them:
When men began to multiply on earth and daughters were born to them, the sons of God saw how beautiful the daughters of man were, and so they took for their wives as many of them as they chose. Then the Lord said: “My spirit shall not remain in man forever, since he is but flesh. His days shall comprise one hundred and twenty years.” At that time the Nephilim appeared on earth (as well as later), after the sons of God had intercourse with the daughters of man, who bore them sons. They were the heroes of old, the men of renown. (Genesis 6:1-4)
Here, the “sons of God” are given no specific name or function; they could represent fallen angels, or simply heavenly beings that mate with women.
The Book of Jubilees adds further details about the Watchers.
In the Book of Daniel an Aramaic term used to denote angels is “watchers” (
îrîn).[1] Each of these heavenly beings is called by the double name "watcher and holy one" (îr weqadîsh), which denotes one type of heavenly being not two. The term “watcher” probably derives from the verb “to be awake” or “to be vigilant,” so that the implication of calling the angels “watchers” is that they are constantly on watch as sentinels for Yahweh.[2]
Angels were fairly popular in Jewish folklore, which often describes them as looking like large human beings that never sleep and remain forever silent. While there are good and bad Watchers, most stories revolve around the evil ones that fell from grace when they took “the daughters of man” as their mates.
The Hebrew of nephilim is נפלים, which may mean “those causing others to fall”. Abraham ibn Ezra proposes that they were called this because men’s hearts would fail at the sight of them. Some (e.g. Jean Leclerc and Peter of Aquila) suggest that it is derived from the warlike nature of the Nephilim, comparing the usage of Naphal in Job 1:15 “And the Sabeans fell upon them” where Naphal means “to take in battle”. Alternatively, Shadal understands nephilim as deriving from the Hebrew word פלא Pela which means wonderous[6].
The nephilim come from a union between “sons of God” (בני האלהים “b’nei ha-'elohim” Lit. “Sons of the powers” [7]) and “daughters of man”. In Aramaic culture, the term Nephila specifically referred to the constellation of Orion, and thus Nephilim to Orion’s semi-divine descendants (cf. Anakim from Anak);[8] the implication being that this also is the origin of the Biblical Nephilim. Some commentators[citation needed] have suggested that the Nephilim were believed to have been fathered by members of a proto-Hebrew pantheon (which is controversial among Jewish peoples[9]) and are a brief glimpse of early Hebrew religion, most of the details of which were later edited out from the Torah (or at least would have been edited out when, as some claim, it was redacted together), and that this passage may have offered monotheistic Hebrews a way to fit semi-divine pagan heroes into their cosmogony.
The idea that the Torah was somehow changed is not in keeping with traditional Hebrew practice, in which if even a single character is out of place in a parchment translation of the original Hebrew Torah, the entire parchment must be destroyed and replaced anew. However, there are several variations, some of great significance, between ancient manuscripts of the Torah, between Septuagint, Syriac Peshitta, Dead Sea Scrolls, masoretic text, Samaritan Pentateuch, and the versions in the Hexapla, as well as between various manuscripts within each of these groups.
In the Hebrew Bible, there are a number of other words that, like “Nephilim”, are sometimes translated as “giants”:

Just a little info in Watchers.