“The word Elohim is the plural of El (or possibly Eloah) and is the first name of God given in the Old Testament: “In the beginning, God (Elohim) created the heavens and the earth, (Gen. 1:1).
“The name Elohim is unique to Hebraic thinking – it occurs only in Hebrew and in no other ancient Semitic language. The masculine plural ending does not mean “gods” when referring to the true God of Israel, since the name is mainly used with singular verb forms and with adjectives and pronouns in the singular (e.g. see Gen. 1:26).” 
The etymology of the word Elohim is prehistoric, and therefore unknown. There are many theories, however, including the following:
- Some trace its origin in el or ul which may mean ("to be strong") or possibly ("to be in front"), from which also are derived ayil ("ram", the one in front of the flock) and elah (the prominent "terebinth"); Elohim would then be an expanded plural form of El. (However, Semitic etymologies are actually generally based on triconsonantal roots, which this proposal completely ignores.)
Some see Elohim as a plural of Eloah. While the words El, Elohim, and Eloah are clearly related, with the word El being the stem, it is uncertain whether the word Elohim is derived directly from El or from Eloah. The word Eloah is a singular (or dual) form of Elohim and appears more than seventy times in the Old Testament, primarily in poetic passages where Elohim is generally used in narrative passages.
Others relate both Elohim and Eloah ("a god") to alah ("to terrify") or alih ("to be perplexed, afraid; to seek refuge because of fear"). Eloah and Elohim, therefore, would be "He who is the object of fear or reverence," or "He with whom one who is afraid takes refuge".
Biblical scholars tend to resist making connections with the father god of Ugarit, El, due to the uncertainty of religious links between Canaanite and Israelite religion. Instead they focus on the common Semitic linguistic background of these two cultures.
The form of the word Elohim, with the ending -im, is plural and masculine, but the construction is usually singular, i.e. it governs a singular verb or adjective when referring to the Hebrew god, but reverts to its normal plural when used of heathen divinities (Psalms 96:5; 97:7). There are many theories as to why the word is plural:
In one view, predominant among monotheists, the word is plural in order to augment its meaning to form either a plural of majesty or an abstraction meaning "Divine majesty".
Among Trinitarian Christian writers it is seen as evidence for the doctrine of the Trinity, a plurality in the Godhead.
In a view common among both secular scholars and polytheists, the word's plurality is seen as reflective of an early Judaic polytheism. Originally meaning "the gods", or the "sons of El," the supreme being, the word may have been singularized by later monotheist priests who sought to replace worship of the many gods with their own patron god YHWH alone.
Significance in the documentary hypothesis
The choice of the word for God varies in the Hebrew Bible. Some scholars view these variations as evidence of different source texts, the "documentary hypothesis." According to the proponents of this theory, Elohim is consistently used in texts that reflect the early northern traditions of the Kingdom of Israel, whereas Yahweh (Jehovah) is consistently used in texts that derive from the early southern traditions of the Kingdom of Judah and Jerusalem. Hence, higher criticism has found it useful to distinguish between "E" traditions and "J" traditions, which they see as reflective of multiple sources and multiple authors for Genesis. See also the JEDP theory for extension of the documentary hypothesis to the idea of multiple sources and authorship for the entire Pentateuch.