Most English words have their source in Latin, Greek, or Germanic languages. But not all. Slogan is one such word.
Slogan comes from the Celtic term slough gairm, which roughly translates to service cry. When it moved from Celtic into Gaelic, it became sluogh ghairm, meaning battle cry. From there, it made its way to English, first appearing as slogorne in 1510, & morphing to the spelling we know today by 1670.
By 1704 slogan meant distinctive word or phrase used by a political or business group.
So all this suggests that the modern citizen has a historical argument for feeling overwhelmed or embattled by the war cries of advertising & poltical slogans.
My thanks go out to this week’s sources: the OED, Etymonline. Merriam Webster, Collins Dictionary, & Wordnik (image from Daily Mail)