The word “Christ,” or in its Hebrew form “Messiah,” occurs 529 times in the New Testament. Literally the word means “anointed.” It makes sense then that, occasionally, the verb form of the word in the Old Testament has an everyday meaning referring to rubbing a shield with oil (Isa 21.5), painting a house (Jer 22.14) or applying oil to the body (Amos 6.6). In this generic sense “anointing” simply means “to cover with.” Beyond the generic meaning of the word, “anointing” takes on a specific religious connotation in the Old Testament.
In reference to religious “anointing” the word can refer to applying oil to items such as the tabernacle, altar, laver (Exod 40.9–11), or even a sin offering (Exod 29.36). Most frequently, however, the word is used to describe the ceremony of initiating someone into a leadership position. The ceremony was named such because it involved pouring oil from a horn on the head of the new leader. This was not done for all leadership positions in Israel, but was specifically reserved for three roles.
Those who were “anointed” were the three most significant leadership roles in Israel. First, priests were anointed for leadership (Exod 28.41; 30.30; 40.13–15; Lev 16.32; Num 3.3) and particularly the High Priest (Exod 40.13; Lev 7.35; Num 35.25). Second and most importantly, Kings were anointed. The most significant examples are Saul (1 Sam 9.9, 16; 10.1; 15.1, 17) and David (1 Sam 16.1–3, 12–13; 2 Sam 12.7; cf. Sir 46.13). Though, there is an example of a king outside of Israel (an Aramean) being “anointed” to his royal position (1 Kgs 19.5). Also, Cyrus, the Persian king, is called God’s “anointed one” or “Messiah” (Isa 45.1). This refers to Cyrus’ role as God’s chosen instrument to bring Israel out of Babylonian exile. In poetic literature the kingly aspect of the anointed becomes even more pronounced because the noun is used in parallel position to “king” (Ps 2.2; 18.51) making the two words somewhat synonymous. Third, and least often, prophets are anointed (1 Kgs 19.15–16; cf. 2 Kgs 9.1–3, 6, 12). The only two prophets ever anointed were Elijah and Elisha. Though, Isaiah refers to himself as anointed (Isa 61.1). So, these three key leadership positions, priest, king and prophet were considered “anointed ones.”