Labour. The British spelling of labor.
Labor. This word is traced back as far as ~1300AD. It comes from Old French labour (now French labeur), which was from Latin laborem. In today’s French, Spanish, and Portuguese, the verb actually means “to plow”, not “hard, physical work”. The first time labor was used to describe the process of childbirth was in 1595. (From Etymonline.com.)
Day. This word has been around for quite a long time. It comes from Old English dæg. It’s also related to the Sanskrit word dah (to burn), the Lithuanian word dagas (hot season), and the Old Prussian word dagis (summer). Its original meaning (in English) was “the daylight hours”, but the meaning expanded over time. The first record of day meaning “a period of 24 hours” was from late Old English (~1066AD).(From Etymonline.com.)
Labor Day was first celebrated in the United States on September 5, 1882.
Most other countries celebrate Labo(u)r Day on the first of May, but Bermuda, Canada, and the US all celebrate it on the First Monday in September.
Now go enjoy your day!