I can also relate and my native language, Czech, is in the Slavic family. GP's friend probably used the word periphery because they knew it's common to the two

I can also relate and my native language, Czech, is in the Slavic family. GP's friend probably used the word periphery because they knew it's common to the two languages, unlike the hypothetical Portuguese synonym. This applies to many words of Greek and Latinate origin. Their frequency is low in most languages, but they are understood in many languages. I find it sad that Brits are peer-pressured into giving up this aspect of their language due to perceived elitism. These 'elitist' words facilitate understanding across the various European languages.