Gaelic languages are a subgroup of the six languages called Insular Celtic languages, which originated in and around the modern-day British Isles during the 3rd century A.D. The three Gaelic tongues are Scottish Gaelic (Gaidhlig), Irish Gaelic (Gaelige) and Manx Gaelic (Gaelg), which is spoken on the Isle of Mann. The other three Insular Celtic languages are Breton, Cornish and Welsh.
In Irish and Scottish Gaelic there are two ways of saying goodbye: one for those leaving, and one for those who reply. Those departing say "Slan" in Irish Gaelic; those who reply say "Slan leat." In Scottish, "goodbye" is "Beannachd leat,"and the reply is "Mar sin leat." Manx Gaelic is a combination of both Irish and Scottish Gaelic; "goodbye" for both parties is "Slane lhiat" or "Bannaght lhiat."
For those whom you may not see for a long time, a more expressive farewell is available in all three languages. An Irish Gaelic speaker might tell a friend leaving on a voyage, "Go gcuire Dia an t-adh ort," meaning "May God put luck on you." He might also hear "Rah De ort," or "God be with you." Scottish Gaelic blessings include "Na h-uile la gu math duit" ("May all your days be good") and "Turas math dhut" ("Good voyage"). When speaking to a Manx Gaelic speaker, say farewell with "Cair vie," which wishes her "fair winds."
Not every departure is a sad one, and the Gaelic tongues have plenty of ways to wish an unwelcome guest a speedy departure. "Imeacht gan teacht ort" is Irish Gaelic for "May you leave without returning," and "Fan fada ort" means "Long travels to you." Scottish Gaelic dictionaries are mostly bereft of negative farewells, but "Thoir as m' fhianais ort" ("Get out of my sight") effectively bids an unwanted guest farewell. Manx Gaelic curses are also less readily available, but to send a bad guest on his way you might call out "Immee gys yn Joyull," meaning "Go to the Devil."
While much of the vocabulary in Irish, Scottish and Manx Gaelic overlaps, the differences in pronunciation are the what define each language. One language can also have multiple dialects; the pronunciation of Irish Gaelic differs if you are speaking a Munster, Ulster or Connaught dialect. The best way to properly learn the pronunciation of Gaelic languages is to contact a local Irish, Scottish or Manx heritage group for recommendations of books, study groups and tutors. Many websites are also available to help students of Gaelic dialects and include audio clips for phonetic pronunciation.