The kris or keris is a distinctive, asymmetrical dagger indigenous to Indonesia, Malaysia, Brunei, Southern Thailand and the southern Philippines. Both a weapon, and spiritual object, krisses are often considered to have an essence or presence, with some blades possessing good luck and others possessing bad.
The kris spread from the island of Java to many parts of the archipelago of Indonesia, such as Sumatra, Bali, Lombok, Sumbawa, South Sulawesi, Kalimantan, and to the Southeast Asian areas now known as Malaysia, Brunei, southern Philippines, southern Thailand, and Singapore.
Kris vs. keris
The term keris probably had a Javanese origin, though it cannot be ascertained how it came about. The term "keris" may have evolved from the old Javanese word ngeris which means ‘to stab’ or ‘to pierce’. Kris is a European rendering of this Javanese term.
Another source from Kelantan claims that the term/word 'KRIS' is an abbreviation (to be read in Jawi_script)
KAF - Keramat, RA - Rahsia, YA - Yang, SIN - Satu
Basically translated as 'The Miraculous Secret of The One' 
As noted by Frey (2003), kris is the more frequently used term, but this pertains mainly to the Western world. The term "keris" is more popular in the native lands of the dagger, as exemplified by the title of a popular Javanese keris book entitled the "Ensiklopedi Keris" (Keris Encyclopedia), written by the late Bambang Harsrinuksmo. Some collectors prefer keris, others kris. Other spellings used by European colonists include cryse, crise, criss, creese.
The Kris is also loosely used to differentiate between the Moro kris swords found in Southern Philippines and the keris daggers found everywhere else in the archipelago
Frey (2003) concludes from Raffles’ (1817) study of the Candi Sukuh that the kris recognized today came into existence around AD 1361. Scholars, collectors and others have formed myriad theories about the origins of the kris. Some believe the form that is credited with being the earliest form of the kris, the keris majapahit, was inspired by the daggers of the Dong-Son in Vietnam (circa 300 BC). Frey (2003) dismisses the Dongson origin of the Majapahit. Unverifiable claims of another form predating the Majapahit exist. Kris history is traced through study of carvings and bas relief panels found in Southeast Asia. One of the more famous renderings of a kris appears on the Borobudur temple and Prambanan temple