Boyd’s Bible Dictionary:

A favorite, and often symbolic, number among Hebrews
(Gen. 2:2; 7:2; 41:2-32And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made. (Genesis 2:2)
2Of every clean beast thou shalt take to thee by sevens, the male and his female: and of beasts that are not clean by two, the male and his female. (Genesis 7:2)
2And, behold, there came up out of the river seven well favored kine and fatfleshed; and they fed in a meadow. 3And, behold, seven other kine came up after them out of the river, ill favored and leanfleshed; and stood by the other kine upon the brink of the river. (Genesis 41:2‑3)
). Used as a round number (1 Sam. 2:55They that were full have hired out themselves for bread; and they that were hungry ceased: so that the barren hath born seven; and she that hath many children is waxed feeble. (1 Samuel 2:5); Matt. 12:4545Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation. (Matthew 12:45)). Type of abundance and completeness (Gen. 4:15,2415And the Lord said unto him, Therefore whosoever slayeth Cain, vengeance shall be taken on him sevenfold. And the Lord set a mark upon Cain, lest any finding him should kill him. (Genesis 4:15)
24If Cain shall be avenged sevenfold, truly Lamech seventy and sevenfold. (Genesis 4:24)
; Matt. 18:21-2221Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times? 22Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven. (Matthew 18:21‑22)). These references, and other places, show a seventh day and seventh year sabbath and a seven times seventh year of Jubilee; also sacrificial animals limited to seven, and the golden candlesticks. Seven priests with seven trumpets surrounded Jericho for seven days, and seven times on the seventh day. In the Apocalypse we find seven churches, seven candlesticks, seven stars, seven seals, seven trumpets, seven vials, seven plagues, seven angels.

Concise Bible Dictionary:

Strong’s Dictionary of Hebrew Words:

prol. for the masculine of 7651; seven
KJV Usage: