anointing: the sacred rite of pouring or smearing consecrating oil to set a person or object apart for God, and the holy oil used to perform it
This word names the anointing that consecrates. In Israel's worship, applying a specially blended oil was how the sacred tent, its furnishings, and above all the priests were formally set apart for holy service. The word points both to that oil and to the rite it performed.
The two shades hold together because the oil has no meaning apart from the act. Its recipe was fixed by command, the oil itself was called holy, and using it for any ordinary purpose was forbidden. So when Scripture speaks of "the oil of anointing," it is naming the single instrument of a single sacred moment, not a household product.
A few times the word steps back from the oil to name the anointing itself as a lasting institution, as when the ordination of Aaron and his sons is called an everlasting priesthood secured by "their anointing." There it is the act, not the substance, that confers the permanent office.