Easton's Bible Dictionary
(Hebrews plural goyum). At first the word goyim denoted generally all the nations of the world (Genesis 18:18; Comp. Galatians 3:8). The Jews afterwards became a people distinguished in a Marked manner from the other goyim. They were a separate people (Leviticus 20:23; 26:14-45; Deuteronomy 28), and the other nations, the Amorites, Hittites, etc., were the goyim, the heathen, with whom the Jews were forbidden to be associated in any way (Joshua 23:7; 1 Kings 11:2). The practice of idolatry was the characteristic of these nations, and hence the word came to designate idolaters (Psalm 106:47; Jeremiah 46:28; Lamentations 1:3; Isaiah 36:18), the wicked (Psalm 9:5, 15, 17).
The corresponding Greek word in the New Testament, ethne, has similar shades of meaning. In Acts 22:21, Galatians 3:14, it denotes the people of the earth generally; and in Matthew 6:7, an idolater. In modern usage the word denotes all nations that are strangers to revealed religion.
Noah Webster's New International Dictionary of the English Language
1. (n.) Plural of Heathen.
2. (n.) An individual of the pagan or unbelieving nations, or those which worship idols and do not acknowledge the true God; a pagan; an idolater.
3. (n.) An irreligious person.
4. (a.) Gentile; pagan; as, a heathen author.
5. (a.) Barbarous; unenlightened; heathenish.
6. (a.) Irreligious; scoffing.