Budo is a Japanese term. It means "martial way" and refers to those martial disciplines whose ultimate goal is spiritual, ethical and/or moral self-improvement. The characters "bu" and "do" in "budo" are rich in meaning and have many secondary interpretations.
Bu is a Japanese word meaning "military" or "related to the military," a character often compounded into others, such as "bugei," "bujitsu" and "bushi." The character for "bu" is a composite of two others. The bottom inside left character is "foot" suggesting advancing on foot, and the right upper larger character is a prototype (perhaps derived from an elaboration of the character for stake) of a halberd (a spear attached to the end of a pole) implying to "cut, menace, pierce or kill." When combined, they can be interpreted as advancing on foot with a weapon, thus referring to a warrior, or by extension, things military. There is also an important secondary interpretation. The first character meaning "foot" has also come to mean stop, based on the idea of planting the foot. Taken in conjunction with the second character of "halberd," "bu" can be thus interpreted as a means to stop a weapon (conflict), or to gain peace. This is consistent with the idea of practicing budo to achieve both inner and outer peace.
Do is the Japanese pronunciation of the Chinese term "Tao" (for Taoism), meaning the way to suppress violence and return to the way of the universe. It is a composite of two characters integrated into one, the first signifying "movement" and the second "head" or "chief." Combined, the characters have the meaning of the chief means of direct movement, or the main road, a term figuratively used to mean the "way," as to enlightenment. Implied also are Taoist concepts of non-resistance, goal-lessness, and loss of ego (not surprisingly shared by Zen since the formation of Zen in China was derived from Indian meditative Buddhism which was strongly influenced by Taoism). But while Chinese Taoism developed strong otherworldly or religious connotations, the Japanese had a more practical, less abstract interpretation, one more focused on the pragmatic dimension of human relationships. This led to the concept of the way or road toward self-development. This could lead to a spiritual awakening - one of intuitive perception, insight and enlightenment (as in Zen).
A similar but not fully analogous term to "Budo" in Chinese is "Wu Shu," whose first character "wu" is the same as "bu" in "budo." "Shu," however, is "art," thus the term more closely parallels the Japanese term "Bujitsu," the war arts of the professional Samurai. Other Chinese terms referring to Chinese martial arts include Kung Fu, Ch'uan fa, Gwo Chi, Gwo Sho and Chung Ku Ch'uan.