Samurai (侍)
"Samurai" is the positional title for officials in Japan from the ancient to middle ages, and an alternative name for "bushi" (warrior) that was derived from the first meaning. It is derived from "saburau", which means "to attend" or "to follow".
Establishment
Originally, this was a term for the class of low-ranking technical palace officials up to the sixth rank who worked for aristocracy and Shodaibu (aristocracy lower than Kugyo), but eventually was used to define the bushi, who were technical palace officials with military skills. The position of bushi originally had two classes, the militaristic aristocracy with the position of shodaibu, and the ordinary bushi with the position of samurai.
As time passed, the range of bushi class was expanded and jizamurai (local samurai) with positions lower than samurai were also considered bushi while the term samurai began to indicate upper class bushi. For example, "the Vocabvlario da Lingoa de Iapam" (Nipojisho, Japanese-Portuguese Dictionary), published in early seventeen century, gave the meaning of the terms Buxi and Mononofu as 'bujin' (warrior) and 'gunjin' (military man), respectively, however, Saburai was translated as 'a nobleman or person to be respected', suggesting that samurai were special people within the bushi class.
Strictly speaking, upper class bushi indicates the class of bushi who had the right to fight on horseback, which had been used to define bushi since the beginning of the bushi class.
The Origin of a Word
"Samurai" is a fairly recent pronunciation that arose in the sixteenth century; before that, it was pronounced "saburai" from the Kamakura period to the Muromachi period and "saburahi" in the Heian period. "Saburahi" is the conjunctive form of the verb "saburafu" (meaning to serve a higher-ranking person), and it can also be used as a noun. The following is a brief history of the word "saburafu". The oldest form of this word to have been found is "samorafu", which made its appearance in the Nara period. "Samorafu" is a combination of the verb "morafu" (meaning wait) and the prefix "sa", which was added to fix the rhythm of the word, and the verb "morafu" is thought to have come from the verb "moru" (meaning lookout, guard) and the suffix "fu", which was added to include the nuance of "existence" or "continuance". As its roots suggest, the word "samorafu" originally conveyed the meaning of carefully watching an opponent's actions; in fact, it was already used in the Nara period to communicate the idea of waiting close by to a nobleman on the lookout while awaiting instructions. A vowel was replaced in the Heian period that changed "Samorahu" to "Samurahu," and a further consonant change led to the word form, "mandafu." "mandafu" was used to read the character "侍," indicating that it was used as a word to indicate service to a nobleman. The kanji (Chinese character) "侍" originally meant "to be on hand to work for and serve an aristocrat," and only in Japan is the word used to refer to ginou kanjin (culturally and academically accomplished palace officials) with military skills who belonged to the bushi class.
The conjunctive form of "saburafu" became "saburahi" in the Heian period, and while this originally meant "a person who is on hand to take care of and serve his/her lord" (or the act of doing so), it later came to mean ginou kanjin of low to middle rank who served upper class aristocrats at the Imperial Court, before finally coming to indicate only one type of ginou kanjin: the "bushi." In other words, the word "saburafu" originally included the nuance of not only "bushi" but also other low- to middle-ranking ginou kanjin such as myoboke (legal experts), so it did not have the connotation of warrior or soldier. As mentioned before, "saburahi" changed to "saburai" and then "samurai," but this word was used to indicate bushi in general regardless of position from around the Edo period, but until then, it was only used to indicate the aristocrats or higher-ranking bushi who were the vassals of the shogun.