The word slogan was first attested sometime in the 1670s, but it was around since the 1510s in the form of slogorne. These terms come from Gaelic sluagh-ghairm, which meant "battle cry". This is rather surprising, but makes sense if you consider the context: slogans used picked up by political factions, which ranged from violent to peaceful. By 1704, the word adopted a secondary definition of "distinctive phrase", something that was later applied to companies as well. Sluagh is from the Old Irish word slog, also "army", and that (through Proto-Celtic slougos) eventually is from Proto-Indo-European slowgo, or "entourage". Ghairm, meanwhile, hails from Old Irish gairm, "cry", which (through Proto-Celtic garman) eventually derives from the Proto-Indo-European reconstruction ghr, also meaning something like "shout". I just think that's an awesome and unexpected etymology!
Adam Aleksic is a 217-month-old, 2800-ounce high school senior with disturbing interests in etymology, vexillology, geography, board games, and law. Adam is anxiously awaiting his college rejections and loves writing about himself in the third person.
The Etymology Nerd