From the Shaolin Scoiety of the UK:

BALISONG

The Bali song is presented as a Filipino knife in literature on the subject. Bali song belongs to the practise of Filipino Martial Arts. The word and the culture of Bali song have origins in Batangas, Philippine islands. Many legends exist about the fabulous use of Bali song by Filipino warriors. One of them would have killed 29 opponents with his Bali song, this legend is sometimes told to justify the Bali song nickname "veintinueve" (twenty nine). But it is not sure that the concept of the Bali song (a blade and two mobile half-handles) comes from the Philippines.

The oldest "Bali song concept" knife found is the Pied-Du-Roy, which has been dated before 1791. This knife is French, and can be seen in the Musee de la Coutellerie, in Thiers (centre of France, Laguiole, the most famous French "city of knives").

Knife Collectors have managed to find "Bali song concept" knives from European countries estimated to be made during the 14th century.
The Bali song itself is a specialised weapon requiring careful practise in order to master its use. Techniques based on the Bali song are taught at the society, and a complete history can be found in the members section----(See "More Balisong History" Gallery)

To see the 1986 court case ruling Taylor v. McManus where the court decided that balisongs DO NOT fall under the Switchblade Act, click here: http://www.cs.cmu.edu/afs/cs.cmu.edu/user/wbardwel/public/nfalist/auto_knives/taylor_v_mcmanus.txt

From ebladestore:

Butterfly Knives History


The term "Bali-Song," with the hyphen, is a registered trademark of Benchmade Corporation and was previously used by Pacific Cutlery and originally by Bali-Song Cutlery before that. But the word "balisong," without the hyphen, is a generic word.

There are a lot of myths and rumors that surface and resurface with various explanations for the meaning and origin of the word "Balisong," but one thing is agreed: it originated from the Philippines.

In the contemporary language of Tagalog, the most common of many languages spoken in the Philippines, "balisong" means "a folding knife with two handles that counter-rotate around the tang."

Here in the United States, as well as in other English-Speaking countries, the term "butterfly knife" is used to describe such a knife. But where does the word "balisong" come from and what does it mean?

A written theory from authors Tom Wei Ding and Tom Wei Toi claim in the book they wrote in 1983, The Manipulation Manual for the Balisong Knife, that balisong means "sharp knife." On the other hand, an author, Jeff Imada, who published the 1984 book, The Balisong Manual, theorizes that "bali" means "break" and "sung" means "horn," and that the handles of the balisongs (originally called "balisungs"), were made from broken animal horns.

This theory was coraborated by Tai Jo in his 1985 book, Balisong Knife, where he explains his theory that the word "balisong" can be translated in variables as either "broken horn" (referencing the use of horn as a handle material), "breaking/rattling horn" (referencing the "clicking" sound that balisong knives make when manipulated), or "to break the horn" (referencing the use of a closed balisong as an impact weapon). Other sources have reported that "balisong" is a proper name and has no meaning at all.

Recently another knife maker who grew up in the Philippines, was trained in the knife making business in the Philippines, plus studied the origins of these unique knives, explained that there is a commonality in the Philippines as within The United States of America, of the country being broken down into states and cities. The nation of the Philippines have provinces (like States) called "Batangas." In Batangas there are Barrios (like cities). One of these Barrios is called "Balisong."

This city is famous for making knives much like the city of Sheffield in England, and Soligen in Germany are famous for knifemaking. Or like the American city of Detroit, Michigan is famous for making automobiles.

This Filipino-American claims that "Balisong" is just the name of this city and has since come to be synonymous with the butterfly knifes made there. Incidently, the city of Balisong is still a thriving city and making butterfly knives is still a prominent industry there. The city even has a semi-professional basketball team named "The Batangas Blades."

As many claims surface and resurface and as new facts are uncovered in this mystical search for the meaning of the word "Balisong," we at eBladeStore.com will continue to offer Butterfly knives from quality manufacturers at our very affordable prices.