GOD - The English word God is identical with the Anglo-Saxon word for “good,” and therefore it is believed that the name God refers to the divine goodness. (See Oehler's Theol. of Old Test.; Strong's and Young's concordances.) (From New Unger's Bible Dictionary) (Originally published by Moody Press of Chicago, Illinois. Copyright (C) 1988.)

Webster's 1913 Dictionary:

\God\ (g[o^]d), n. [AS. god; akin to OS. & D. god, OHG. got, G. gott, Icel. gu[eth], go[eth], Sw. & Dan. gud, Goth. gup, prob. orig. a p. p. from a root appearing in Skr. h[=u], p. p. h[=u]ta, to call upon, invoke, implore. [root]30. Cf. {Goodbye}, {Gospel}, {Gossip}.]
http://www.hyperdictionary.com/dictionary/god

Catholic Encyclopedia:


Etymology of the Word "God"

(Anglo-Saxon God; German Gott; akin to Persian khoda; Hindu khooda).

God can variously be defined as:
• the proper name of the one Supreme and Infinite Personal Being, the Creator and Ruler of the universe, to whom man owes obedience and worship;
• the common or generic name of the several supposed beings to whom, in polytheistic religions, Divine attributes are ascribed and Divine worship rendered;
• the name sometimes applied to an idol as the image or dwelling-place of a god.

The root-meaning of the name (from Gothic root gheu; Sanskrit hub or emu, "to invoke or to sacrifice to") is either "the one invoked" or "the one sacrificed to." From different Indo-Germanic roots (div, "to shine" or "give light"; thes in thessasthai "to implore") come the Indo-Iranian deva, Sanskrit dyaus (gen. divas), Latin deus, Greek theos, Irish and Gaelic dia, all of which are generic names; also Greek Zeus (gen. Dios, Latin Jupiter (jovpater), Old Teutonic Tiu or Tiw (surviving in Tuesday), Latin Janus, Diana, and other proper names of pagan deities. The common name most widely used in Semitic occurs as 'el in Hebrew, 'ilu in Babylonian, 'ilah in Arabic, etc.; and though scholars are not agreed on the point, the root-meaning most probably is "the strong or mighty one."


http://www.newadvent.org/cathen/06608x.htm

Oxford English Dictionary:

"god (gρd). Also 3-4 godd. [Com. Teut.: OE. god (masc. in sing.; pl. godu, godo neut., godas masc.) corresponds to OFris., OS., Du. god masc., OHG. got, cot (MHG. got, mod.Ger. gott) masc., ON. goð, guð neut. and masc., pl. goð, guð neut. (later Icel. pl. guðir masc.; Sw., Da. gud), Goth. guÞ (masc. in sing.; pl. guÞa, guda neut.). The Goth. and ON. words always follow the neuter declension, though when used in the Christian sense they are syntactically masc. The OTeut. type is therefore *guđom neut., the adoption of the masculine concord being presumably due to the Christian use of the word. The neuter sb., in its original heathen use, would answer rather to L. numen than to L. deus. Another approximate equivalent of deus in OTeut. was *ansu-z (Goth. in latinized pl. form anses, ON. ρss, OE. Ós- in personal names, ésa genit. pl.); but this seems to have been applied only to the higher deities of the native pantheon, never to foreign gods; and it never came into Christian use.

The ulterior etymology is disputed. Apart from the unlikely hypothesis of adoption from some foreign tongue, the OTeut. *gubom implies as its pre-Teut. type either ghudho-m or *ghutó-m. The former does not appear to admit of explanation; but the latter would represent the neut. of the passive pple. of a root *gheu-. There are two Aryan roots of the required form (both *glheu, with palatal aspirate): one meaning ‘to invoke’ (Skr. hū), the other ‘to pour, to offer sacrifice’ (Skr. hu, Gr. χέειν, OE. yéotan YETE v.). Hence *glhutó-m has been variously interpreted as ‘what is invoked’ (cf. Skr. puru-hūta ‘much-invoked’, an epithet of Indra) and as ‘what is worshipped by sacrifice’ (cf. Skr. hutá, which occurs in the sense ‘sacrificed to’ as well as in that of ‘offered in sacrifice’). Either of these conjectures is fairly plausible, as they both yield a sense practically coincident with the most obvious definition deducible from the actual use of the word, ‘an object of worship’.

Some scholars, accepting the derivation from the root *glheu- to pour, have supposed the etymological sense to be ‘molten image’ (= Gr. χυγόν), but the assumed development of meaning seems very unlikely.

transcribed from The Oxford English Dictionary

Webster's Revised Unabridged Dictionary:

god

\God\ (g[o^]d), n. [AS. god; akin to OS. & D. god, OHG. got, G. gott, Icel. gu[eth], go[eth], Sw. & Dan. gud, Goth. gup, prob. orig. a p. p. from a root appearing in Skr. h[=u], p. p. h[=u]ta, to call upon, invoke, implore. [root]30. Cf. Goodbye, Gospel, Gossip.]

1. A being conceived of as possessing supernatural power, and to be propitiated by sacrifice, worship, etc.; a divinity; a deity; an object of worship; an idol.

He maketh a god, and worshipeth it. --Is. xliv. 15.

The race of Israel . . . bowing lowly down To bestial gods. --Milton.

2. The Supreme Being; the eternal and infinite Spirit, the Creator, and the Sovereign of the universe; Jehovah.


http://dictionary.reference.com/search?q=god

American Heritage Dictionary:

GOD

NOUN: 1. God a. A being conceived as the perfect, omnipotent, omniscient originator and ruler of the universe, the principal object of faith and worship in monotheistic religions. b. The force, effect, or a manifestation or aspect of this being. 2. A being of supernatural powers or attributes, believed in and worshiped by a people, especially a male deity thought to control some part of nature or reality. 3. An image of a supernatural being; an idol. 4. One that is worshiped, idealized, or followed: Money was their god. 5. A very handsome man. 6. A powerful ruler or despot.

ETYMOLOGY: Middle English, from Old English. See gheu(): in APPENDIX I
APPENDIX I: ENTRY: gheu()-

DEFINITION: To call, invoke. Oldest form *heu()-, becoming *gheu()- in centum languages. Suffixed zero-grade form *ghu-to-, “the invoked,” god. a. god, from Old English god, god; b. giddy, from Old English gydig, gidig, possessed, insane, from Germanic *gud-iga-, possessed by a god; c. götterdämmerung, from Old High German got, god. a–c all from Germanic *gudam, god. (Pokorny hau- 413.)

http://www.bartleby.com/61/21/G0172100.html

An Additional On-Line Reference:
Word origin: God - Our word god goes back via Germanic to Indo-European, in which a corresponding ancestor form meant “invoked one.” The word’s only surviving non-Germanic relative is Sanskrit hu, invoke the gods, a form which appears in the Rig Veda, most ancient of Hindu scriptures: puru-hutas, “much invoked,” epithet of the rain-and-thunder god Indra. (From READER’S DIGEST, Family Word Finder, page 351) (Originally published by The Reader’s Digest Association, Inc., Pleasantville New York, Montreal; Copyright 1975)

Now if the sources noted above are accurate, then the word that we use for the Supreme Being, God, comes from a very pagan origin. Thus the word god is used generically by many different religions to refer to their deity or “invoked one.”

Some may laugh at the notion, the very idea that the word “God” has any origin or association with Hindu Sanskrit. To illustrate how this is possible, we again quote from ‘Family Word Finder’ on the historical development of our Modern English language:

Page 7, ‘Word Origins’ - “English belongs to the Indo-European family of languages, which consists of about 100 related tongues, all descended from prehistoric language of a pastoral, bronze working, horse breeding people, the Aryans, who inhabited the steppes of Central Asia about 4500 B.C. Scholars refer to their language at this stage as proto-Indo-European, or simply Indo-European.
http://www.bibleanswerstand.org/God.htm

... Sitting down, he began to read the tattered pages. As he read, his excitement grew. The book told of ancient wars of the gods, with a backdrop of superstition. But the language, written in a dialect almost forgotten, amazed Yoseb. He saw at once that this language was the key for which they had searched. Here was the word for "God" which they had so diligently sought, a good word for "prayer," and other difficult phrases. The language, much simpler than the classical Tibetan, could be adapted so that the modern Tibetan would understand it clearly--even the simple people of the hills.

So i put the dash in G-d so as not to write or cause another to speak or even think of this name of a pagan deity."

Oddly, the exact history of the word God is unknown. The word God is a relatively new European invention, which was never used in any of the ancient Judaeo-Christian scripture manuscripts that were written in Hebrew, Aramaic, Greek or Latin.

Why use G-d and not -od, Go-, or G--, -o-, --d, or ---?