chief (high) priest, chief of the priests

Concise Bible Dictionary:

It is remarkable that this title occurs but seldom in the Old Testament (Lev. 21:1010And he that is the high priest among his brethren, upon whose head the anointing oil was poured, and that is consecrated to put on the garments, shall not uncover his head, nor rend his clothes; (Leviticus 21:10); Num. 35:2525And the congregation shall deliver the slayer out of the hand of the revenger of blood, and the congregation shall restore him to the city of his refuge, whither he was fled: and he shall abide in it unto the death of the high priest, which was anointed with the holy oil. (Numbers 35:25); Josh. 20:66And he shall dwell in that city, until he stand before the congregation for judgment, and until the death of the high priest that shall be in those days: then shall the slayer return, and come unto his own city, and unto his own house, unto the city from whence he fled. (Joshua 20:6); 2 Kings 12:1010And it was so, when they saw that there was much money in the chest, that the king's scribe and the high priest came up, and they put up in bags, and told the money that was found in the house of the Lord. (2 Kings 12:10); 2 Chron. 24:1111Now it came to pass, that at what time the chest was brought unto the king's office by the hand of the Levites, and when they saw that there was much money, the king's scribe and the high priest's officer came and emptied the chest, and took it, and carried it to his place again. Thus they did day by day, and gathered money in abundance. (2 Chronicles 24:11), and others). Aaron was constantly called “the priest”; but as his sons were also called priests, he was necessarily the “chief” and would correspond to what is called high priest in the New Testament. His office is summed up in few words: he “is ordained for men in things pertaining to God” that he might offer both gifts and sacrifices for sins. He stood for the people to God: he offered up the sacrifices which put the people in relation with God (Lev. 9), also those on the day of atonement (Lev. 16), and he blessed them as from God. He, as taken from among men, was one who could have compassion on, or forbearance toward, the ignorant and the erring; for that he himself was compassed with infirmity (Heb. 5:1-21For every high priest taken from among men is ordained for men in things pertaining to God, that he may offer both gifts and sacrifices for sins: 2Who can have compassion on the ignorant, and on them that are out of the way; for that he himself also is compassed with infirmity. (Hebrews 5:1‑2)). Aaron did not take the honor upon himself, nor did Christ (Heb. 5:4-54And no man taketh this honor unto himself, but he that is called of God, as was Aaron. 5So also Christ glorified not himself to be made an high priest; but he that said unto him, Thou art my Son, to day have I begotten thee. (Hebrews 5:4‑5)). Having accomplished redemption by the offering of Himself, He passed through the heavens and sat down on the right hand of God. He is touched with the feeling of our infirmities, having been Himself tempted as we are, apart from sin. He ever lives to make intercession for us, He is also the minister of the sanctuary—He appears in the presence of God for us, and is the great Priest over the house of God (Heb. 4:14-1514Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession. 15For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. (Hebrews 4:14‑15); Heb. 8:11Now of the things which we have spoken this is the sum: We have such an high priest, who is set on the right hand of the throne of the Majesty in the heavens; (Hebrews 8:1)). See AARON, AARONIC PRIESTHOOD, MELCHISEDEC.

Strong’s Dictionary of Greek Words:

from 746 and 2409; the high-priest (literally, of the Jews, typically, Christ); by extension a chief priest
KJV Usage:
chief (high) priest, chief of the priests