Goy

[Rihanna]

Hebrew and Yiddish term for a non-Jewish person; synonymous with gentile. Usually neutral, despite persistent untrue rumors that it is derogatory. It should only be considered offensive when it is used in a context indicating that its intended as an insult, or said in a tone of disgust- much like the word Jew. Plural, goyim; adjective forms goyish, goyishe, goyisher.

[Couch Potatoe]

A Hebrew word used in the Jewish Scriptures (a.k.a. the Old Testament). The word means nation, and is always used within these scriptures to refer to the nations of the world. Significantly, within the Old Testament, Judah (the Jewish nation) itself is called a goy.
In the Old Testament, the Jews were called to be a nation separate from the other nations, which were all Pagan. And so, colloquially, all non-Jewish nations came to be called goyim as in the nations from which the God of the Old Testament had called upon the Jews to separate themselves.
A word used by some Jews to refer to Gentiles (non-Jews). The word can have derogatory connotations, such as the word black when used to refer to a persons of African descent. It can be neutral or negative depending on the context and the intent of the speaker.

Plural - goyim.

[Sarah]

Goy; plural: goyim; adjective: goyisha or goyish (GOY-um, goyz, GOY-ish-uh, GOY-ish)

A non-Jew (non-Jews, not Jewish).
Someone resembling non-Jews as Jews have typically perceived them; therefore someone who is stupid, insensitive or violent (although the word is usually used today in a light, joking way).

The distinction between Jewish and goyish can be quite subtle, however, as the following from Lenny Bruce illustrates:
“I’m Jewish. Count Basie’s Jewish. Ray Charles is Jewish. Eddie Cantor’s goyish. The B’nai Brith is goyish. The Hadassah is Jewish. Marine Corps – heavy goyish, dangerous.
Kool-Aid is goyish. All Drake’s cakes are goyish. Pumpernickel is Jewish and, as you know, white bread is very goyish. Macaroons are very Jewish. Fruit salad is Jewish. Lime Jell-O is goyish. Lime soda is very goyish. Trailer parks are so goyish that Jews won’t go near them.
Balls are goyish. Titties are Jewish. Mouths are Jewish. All Italians are Jewish. Greeks are goyish. Eugene O’Neill – Jewish. Dylan Thomas – Jewish. Steve Allen is goyish, though. It’s the hair. He combs his hair in the boys’ room with that soap all the time.
See how easy it is? Fidel Castro? Jewish, of course. Henry Kissinger – goyish. Marlon Brando – Jewish. Ringo is Jewish. Paul is goyish. George is goyish. John, of course, was Jewish.
Talk is Jewish. Silence is goyish. Thin is goyish. Fat is Jewish. Blue is Jewish. Green is goyish. Atheism is Jewish. Converting to Christianity is, of course, goyish. But as R. Crumb points out, so is converting to Judaism. In fact, it’s such a goyish thing, no Jew has ever done it.
Computers are Jewish. Rifles are goyish. California is goyish. France is Jewish. The thirties were Jewish. The forties were goyish. The fifties were goyish. The sixties were Jewish. The seventies were goyish. The eighties are off to an intensely goyisha start.
Teddy Kennedy is Jewish. Ronald Reagan is goyish. Nancy Reagan is the most goyisha person who has ever lived. Marie Osmond is second. Tricia Nixon is third. David Eisenhower is like a broad caricature of a goy. Richard Nixon, however, is too much of an open maniac to be a goy.
OK, now you try it. One of the items in each pair listed below is Jewish, and the other one is goyish. Can you tell which is which?
Bowling alleys/constant guilt
Spam/chicken soup
Crew cuts/big, dark almond-shaped eyes
Jumping out of planes/double-entry bookkeeping
Respecting your scoutmaster/believing you’re Jesus Christ
Goyim is the more common plural, and is always use when speaking generally: What can you expect from goyim?
Goys is used to refer to particular people. A couple of goys.
One of the oldest problems puzzled over in the Talmud is “Why did God create goyim?” The generally accepted answer is “Somebody has to buy retail.”

From Every Goy’s Guide to Common Jewish Expression (Also recommended for Jews who don’t know their punim from their pupik) by Arthur Naiman