Ceylon is the former name of Sri Lanka. Maps, governments, and the news now say Sri Lanka; the old name belongs to history, to older speakers, and to tea. Ceylon tea is still a famous export, and boxes still say Ceylon, so the name is not dead — it moved from the country to the product. If you call the country Ceylon today, you may sound as if you are reading a very old book, or as if you have not noticed the change. In a history class, though, Ceylon is the right word for that period, including the years it was a British colony.

錫蘭（斯里蘭卡舊稱；茶葉仍常標 Ceylon／錫蘭）