井泉[seisen] (water) well
黄泉[kousen] underground spring
温泉[onsen] spa
九泉[kyuusen] hades
源泉[gensen] source

古泉学[kosengaku] numismatics
鉱泉[kousen] mineral spring
泉貨紙[senkashi] reclaimed paper
泉水[sensui] fountain

汚染源[osengen] source of pollution
音源[ongen] sound source
禍源[kagen] source of misfortune
供給源[kyoukyuugen] source of supply
経営資源[keieishigen] management resource

源氏物語[genjimonogatari] the Tale of the Genji
源泉[gensen] source
源流[genryuu] current-limiting
語源[gogen] word root