Why is it called "Triple Sec"?

What is triple about it? Three kinds of citrus maybe?
And what is “sec”?

Sec means “dry”. I guess that triple sec means “really dry”.
I think that “dry” in booze means “not sweet”.
Peace,
mangeorge

According to Ask Jeeves:

I’d venture to say it’s the only instance where sec is synonym of distilled in French.

Hm. Think of the relationship between the English words “dry” and “anhydrous.” Both mean, more or less, “without water.” This is exactly the state one would hope to achieve by triple distillation of an alcohol-bearing solution. Of course, totally anhydrous alcohol is quite difficult to manufacture. I understand that the best one can hope for without really advanced equipment is around 90% alcohol/10% water (180 proof).

Just a random thought. I have no idea if this actually has anything to do with the name of the stuff.

From the current issue of COOK’S ILLUSTRATED, the thinking cook’s magazine, which includes an analysis and master recipe for fresh Margaritas:

“Next, I tested orange-flavored liqueurs. Both Grand Marnier and Cointreau were delicious, but many tasters thought their robust flavor too pronounced and “boozy” for a margarita. Triple Sec, an orange liqueur with a lower alcohol content, made a more delicate contribution.”

Given the number of sea captains who have averred that posh meant “port out, starboard home,” I am not about to claim that someone who discusses liquor automatically knows where the language of liquor originates.

However, these sites do claim that “triple sec” means “triple distilled” (of course, the very similar language used indicates a single source which is not available for analysis):

The Webtender: Triple sec

Triple Sec: Drinkboy

On the other hand, this site claims (without attribution and in contradiction to every other site) that the name indicates that it is the product of three separate fruits.

partyman

The one point I did notice is that Triple Sec is universally noted for its sweetness (although it is described as not as heavy or not as cloying as its sister products, Cointreau, Grand-Marinier, or Curacao). Given that it is considered a sweet drink, I would guess that the sites pushing “distilled” over “dry” may have a point.