(set a, set to) seal up, stop

Concise Bible Dictionary:

Seal Ring (1600-1700)
Stones on which words, letters, or symbols are engraved. Anciently these were pierced, and by a cord or chain were hung from the arm or the neck, or they were set in rings and worn on the finger. The design was impressed on pieces of clay which were attached to official documents, which in the East are not considered authentic without being sealed (Ex. 28:1111With the work of an engraver in stone, like the engravings of a signet, shalt thou engrave the two stones with the names of the children of Israel: thou shalt make them to be set in ouches of gold. (Exodus 28:11); Esther 8:8,108Write ye also for the Jews, as it liketh you, in the king's name, and seal it with the king's ring: for the writing which is written in the king's name, and sealed with the king's ring, may no man reverse. (Esther 8:8)
10And he wrote in the king Ahasuerus' name, and sealed it with the king's ring, and sent letters by posts on horseback, and riders on mules, camels, and young dromedaries: (Esther 8:10); Job 38:1414It is turned as clay to the seal; and they stand as a garment. (Job 38:14); Dan. 6:1717And a stone was brought, and laid upon the mouth of the den; and the king sealed it with his own signet, and with the signet of his lords; that the purpose might not be changed concerning Daniel. (Daniel 6:17)). The seal was also used to ensure security, or to preserve the sanctity of things not to be revealed (Isa. 29:1111And the vision of all is become unto you as the words of a book that is sealed, which men deliver to one that is learned, saying, Read this, I pray thee: and he saith, I cannot; for it is sealed: (Isaiah 29:11); Dan. 12:4,94But thou, O Daniel, shut up the words, and seal the book, even to the time of the end: many shall run to and fro, and knowledge shall be increased. (Daniel 12:4)
9And he said, Go thy way, Daniel: for the words are closed up and sealed till the time of the end. (Daniel 12:9); Matt. 27:6666So they went, and made the sepulchre sure, sealing the stone, and setting a watch. (Matthew 27:66); Rev. 20:33And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season. (Revelation 20:3); Rev. 22:1010And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand. (Revelation 22:10)).
A covenant was sealed by Nehemiah and those with him (Neh. 10:11Now those that sealed were, Nehemiah, the Tirshatha, the son of Hachaliah, and Zidkijah, (Nehemiah 10:1)). The believer, in crediting what God says of man, and of God’s salvation, virtually attaches his seal (vouches for the fact) that God is true (John 3:3333He that hath received his testimony hath set to his seal that God is true. (John 3:33)). “The foundation of God standeth sure, having this seal, The Lord knoweth them that are His [God’s side]; and, Let everyone that nameth the name of the Lord depart from iniquity [man’s side]” (2 Tim. 2:1919Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, Let every one that nameth the name of Christ depart from iniquity. (2 Timothy 2:19)). This is an illustration of a double-seal turning on a pivot, of which either side could be used.
The roll in Revelation 5 had seven seals, so arranged that by breaking one seal a certain portion could be unrolled; and each seal was broken in succession until the whole was revealed.

Strong’s Dictionary of Greek Words:

Number:
4972 (find all occurrences in KJV Bible)
Greek:
σφραγίζω
Transliteration:
sphragizo
Phonic:
sfrag-id’-zo
Meaning:
from 4973; to stamp (with a signet or private mark) for security or preservation (literally or figuratively); by implication, to keep secret, to attest
KJV Usage:
(set a, set to) seal up, stop