Cathleen, one of the family's maids, is introduced by O'Neill as a "buxom Irish peasant." Because of this, O'Neill doesn't bother to put a large amount of Irish dialect into Cathleen's lines, leaving the character's Irish accent up to the actor. Still, there are some notable words and phrases from Irish dialect that O'Neill includes to clarify Cathleen's manner of speech. These help elaborate her character and distinguish her from the Tyrone family, marking her as a more recent immigrant who has had less time to assimilate into American society.
Perhaps the most notable bit of Irish dialect that Cathleen uses comes when she calls the foghorn a "banshee." This is the anglicized spelling of the Irish bean sídhe, "fairy woman." The banshee, according to Gaelic mythology, was a death omen; she would appear as a bedraggled older woman and scream in the distance, heralding an upcoming death in the family. Though versions of the banshee have become somewhat well-known in popular culture, when O'Neill was writing in the late 1930s, it would be seen as a distinctly Irish myth. And, by Cathleen referencing it, the audience sees her as distinctly Irish. The reference also complicates the image of the foghorn in the play. Cathleen comparing the foghorn with the banshee ascribes an even greater sense of doom to it, deepening the growing tension around the repeating sound by referencing an omen of death.
When Cathleen discusses Tyrone's tendency to drink, she says. "Well, it's a good man's failing. I wouldn't give a trauneen for a teetotaler." A trauneen is an anglicized version of the Irish word tráithnín. A trauneen is a thin blade of grass or hay, or a person who is just as thin and delicate as such a blade of grass and thus has a weak constitution and commitment; the word is often used for someone more susceptible to a drinking problem and less able to manage their passions. Cathleen pairs it with an Anglo-American word, "teetotaler," one who does not drink. This bit of Irish dialect is used primarily for its elegant alliteration ("[...] wouldn't give a trauneen for a teetolar": Cathleen has a sense for a good sentence. Cathleen also intones that alcoholism is a good Irish man's failing—she wouldn't give a trauneen (an Irish term for a drinker) for a teetotaler (an American term for a non-drinker). Tyrone, who drinks and is Irish, passes Cathleen's test.