An informal address that marks comfort and belonging — you'd use it with close friends or casual acquaintances, never in formal settings.
Causa is what Peruvians call the person standing next to them. Not their best friend specifically, not a stranger exactly — just someone they're comfortable with in that moment. You hear it in greetings, as a standalone exclamation, softened to "causita" when there's affection involved. It marks the boundary between formal distance and casual ease.
The word emerged from Lima's streets in the 1980s and 1990s, though no one agrees on why. One story traces it to World War I-era patriotic solidarity, when "La Causa" meant fighting for your country — brotherhood that slowly softened into friendship. The other story is rawer: prisoners shortened "encausados" (the formally charged) to "causa," turning legal status into kinship. Either way, what started as code for solidarity became everyday language.
The uncertainty about which origin is true matters less than what both stories share: causa has always meant "someone on my side." Whether that side was a nation or a cell block, the word carries weight about who belongs. Lima took language from the margins — whether patriotic fervor or prison argot — and made it the sound of everyday connection. What separates you from outsiders isn't where you're from, but whether you know when to say causa.