Okinawa was also called Ryukyu, or 琉球 and was once a small kingdom free from Japanese and Chinese occupation. Since this small tropical island is located right between Japan and southern part of China, it consequently experienced severe political trauma in its history, especially when a southern end Japanese clan Satsuma, or 薩摩 invaded Okinawa in 1607 and occupied its administration by force. No islanders except the authorized royal class members were allowed to arm in their daily life. Prior to the Satsuma invasion, the islanders had similar experiences by their own King at the end of the Civil War in 1422. In both occasions, the islanders learned to train, in secret, the hand to hand combat tactics which developed into the art of Karate later.
At this time, the art lacked its Chinese sophistication and offered more practical application of the system by using bare hands and legs. For example, the hands were trained on finger's tip, the knuckle and at both sides and at the tail of the palm by pounding against hard objects daily. Likewise the elbow knuckle, toes and the ridge of the foot were also trained as for to use them like weapons. Japanese instructors now eliminated such an old training system due to its risk to damaging the hands.
At the beginning in Okinawa the system was called 'Te', or 手, meaning 'hand'. The arts of Te, however, appeared to differ its system depending upon geographical locations and instructors. The islanders therefore distinguished its school by identifying a name of city such as Naha-Te, or 那覇手, Shuri-Te, or 首里手, Tomari-Te, or 泊手 and so on. Naha and Tomari were known to be the popular port cities. Shuri once was a capital city where the king resided. Other than that, there was the systems called To-De or Tote that was written as 唐手 of which alternative pronunciation is "Karate"; meaning Chinese hand. Of the local historians appeared to distinguish To-De and Te as for different form. However, Japanese called the art, in general, 'Karate' and wrote it 唐手.
During this transitional period of time when the art was becoming more popular in main land Japan, the art was called "Karate Kempou" or 唐手拳法 which meant Chinese Hand Fist System. Later during 1930s Japanese practitioners changed the written characters to 空手. First word "空" means vacant, absent or empty and second word "手" means hand. Its implication is to symbolize a pair of bare hands combat for the sake of self defense against the armed hands. However, it was Japanese political attempt to transform the body of the art with metaphysical insinuation so that the name can eliminate its national identity.
There existed in Japan for fifteen to twenty century an incorporated field of martial arts as for a traditional institution named 'Budo', or 武道. Ever since Okinawa was forced to become one of the provinces of Japan in 1871, there had been a political upraising by both the Japanese and the local citizens to promote the art to be recognized in the field of Budo.
Hence, the practitioners of the art started to call it Karate-Do by applying the suffix -do to Karate. "Do" or 道 literally means "way" as for "a way of life." One of the branch doctrine from Confucianism, or 朱子学 once strongly influenced the Japanese intellects and Samurai class during the feudal time in the tenth century. The concept of -do or way of life came from the doctrine. All of the arts categorized in the Martial Arts, thus, are named with -do, like Judo, Kendo, Aikido and so on.
The Art of Karate-Do, or 空手道 is what the official name was during the 1930's in the mainland Japan. Traditionally, all the martial arts that were recognized among the field offered to claim their specific name of school or style in order to identify their lineage within the art. Unlike its custom, the art of Karate-Do in Okinawa thus started claim to its name of style such as Goju-Ryu, or 剛柔流, and Shito-Ryu, or 糸東流. Ryu, or 流 literally means stream which indicates lineage of branch.
More information about the origin of the word Karate.What's In A Name