- secular (adj.)
- late 13c., "living in the world, not belonging to a religious order," also "belonging to the state," from Old French seculer, from Late Latin saecularis "worldly, secular," from Latin saecularis "of an age, occurring once in an age," from saeculum "age, span of time, generation," probably originally cognate with words for "seed," from PIE root *se(i)- "to sow" (cf. Gothic mana-seþs "mankind, world," literally "seed of men").
Used in ecclesiastical writing like Greek aion "of this world" (see cosmos). It is source of French siècle. Ancient Roman ludi saeculares was a three-day, day-and-night celebration coming once in an "age" (120 years).