from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. name of a tribe, ethnonym
From Ancient Greek ἐθνικόν (ethnikos), neuter gender of ἐθνικός (ethnikos, "national"). (Wiktionary)
Some say it's a corruption of "griego" (Greek, the classic Western European ethnicon for something that makes no sense), while others claim it referred to Irish immigrants in Madrid.