世紀【せいき】
century, era, of the century (e.g. fight of the century)
紀元【きげん】
era, CE (Common Era), AD (Anno Domini)
二十世紀【にじっせいき】
twentieth century
綱紀【こうき】
law and order, (official) discipline
世紀末【せいきまつ】
end of a century (esp. 19th), fin-de-siècle, end of the world (esp. in fiction), apocalypse
紀行【きこう】
traveller's journal, traveler's journal, travelogue
紀元前【きげんぜん】
pre-era, BC, BCE
風紀【ふうき】
public morals, discipline, rules governing social behavior
綱紀粛正【こうきしゅくせい】
enforcement of official discipline, tightening of discipline, eliminating corruption among government officials
前世紀【ぜんせいき】
last century, previous century, ancient times, old times
第三紀【だいさんき】
the Tertiary period
白亜紀【はくあき】
Cretaceous Period