Hoi
Swiss German
Said in eastern Switzerland
Hi
Hoi zäme — to several people
Hoi is a young greeting, quite literally. When the Schweizerisches Idiotikon, the great dictionary of Swiss German, wrote its entry hoi in the 1880s, the word greeted nobody there yet: it was a call of herders and carters to steer or drive on their cattle, and a “come on, get going!” shouted at people. According to Wikipedia, which draws on dialect research, the sense of “hello” only appears in the 20th century.
And it appears in eastern Switzerland. Around 1925, Anna Zollinger-Escher, in her thesis on forms of greeting, records it in Appenzell Ausserrhoden, the Toggenburg and the Werdenberg, mostly among boys. The Atlas of Swiss Folklore sees it at that time as a brand-new fashion among the pupils of the cantonal schools of St. Gallen and Frauenfeld. That the herders’ call became the schoolboys’ greeting remains likely, though unproven.
Since then Hoi has won over all of German-speaking Switzerland, even if part of the west, from Basel to Bern and from Fribourg to the Valais, still sometimes turns its nose up at it. It is a familiar greeting: you say it to people you are on first-name terms with.
For one friend, a single word will do; for a whole group you add zäme, “together”:
Sources: German Wikipedia, “Hoi (Interjektion)” and “Grüezi”, after the Schweizerisches Idiotikon (volume II, column 860), Anna Zollinger-Escher’s thesis (1925) and the Atlas der schweizerischen Volkskunde.