Goombah and similar forms probably derived as an alteration or Anglicized spelling of the common Southern Italian familiar term of address, cumpà, the apocoped oxytone form of the word cumpari found in Southern Italian dialects and compare found in Standard Italian, which denotes the godfather in a baptism.
It is therefore commonly used as a term of endearment roughly equivalent to "friend," "brother," or "comrade" among close friends or associates (generally males) in certain parts of Southern Italy, including Campania and Sicily, where it becomes cumpà or cumpari in the regional Southern languages. It has, however, also gained a less innocuous meaning in certain criminal contexts, signifying an "accomplice," "cohort," "fellow criminal," or "partner-in-crime," though it is still mostly used among non-criminal Southern Italian males as a harmless address of affection.
Compare and the Southern Italian cumpà and cumpari ultimately derive from the medieval Latin compater, meaning "cousin" and, later, "godfather."
With the arrival of Southern Italian immigrants in America, this appellation used among Southern Italian males, cumpà, became the Anglicized "goombah" or "gumba" to American ears. As the term cumpà was commonly heard as a term of address among Italian immigrants and Italian-Americans, the Anglicized version of cumpà, or "goombah," came to be used among non-Italians as a derogatory or patronizing way to refer to Italian-Americans.
Today, especially in Italian-American slang, "goombah" is a slang noun for a companion or associate, especially a friend who acts as a patron, accomplice, protector, or adviser. When used by non-Italians to refer to Italians or Italian-Americans, however, "goombah" is often derogatory in nature or deployed as an ethnic slur, implying a stereotypical Italian-American male, thug, or mafioso. Also used as a term of endearment among men (who are friends) in Italian culture.
In the Chrysler Presents A Bob Hope Comedy Special NBC TV program (original air date September 27, 1963), singer Barbra Streisand introduces Italian-American singer Dean Martin as follows: "And now here's America's number one goombah, singing his new Reprise hit 'Via Veneto', il signore Deano Martin."
Derogatory use of the term dates back to the 1969 publication of Mario Puzo's The Godfather and the highly popular movie made from it, which contained dialogue such as "I don't care how many guinea Mafia goombahs come out of the woodwork."
In 2016, U.S. Senator Mark Kirk used the term in reference to what he regarded as unqualified political hires at a veterans' nursing home: "Blagojevich's people ordered [Tammy Duckworth] to take on some political operatives and I would call them goombahs in the Anna Nursing home facility that she was in charge of", drawing bemused commentary for his "Sopranos throwback moment".