also: ぜえろく
noun
person from Kansai
Archaic, derogatory term used in Edo-period Tokyo (Edo) to refer to people from the Kansai region (especially Osaka). Now obsolete and offensive.
See also: 才六 (さいろく)
江戸時代には、関西出身者を「贅六」と呼ぶことがあった。
In the Edo period, people from Kansai were sometimes called 'zeiroku'.
Same kanji but different reading and meaning: さいろく refers to a young, inexperienced person or a novice, not a regional slur.
The exact origin is uncertain. The kanji are ateji, and the word may derive from a dialectal or slang term in Edo-period Japanese.