An object, act, situation, or unusual display that has significance as an indicator of something else, present or future. The sign (Heb., ʼohth; Gr., se·meiʹon) might be an evidence of authenticity or of authority, a warning of danger, or an indicator as to the wise course to follow.

Among the many signs that Jehovah has provided for human guidance, the first mentioned as such are the heavenly luminaries, the sun and the moon. (Ge 1:14) They are time indicators as well as visible signs of God’s existence and qualities. (Ps 19:1-4; Ro 1:19, 20) Evidently because of looking to these luminaries as well as to the stars for omens, as by astrology, the nations have been “struck with terror,” as stated at Jeremiah 10:2.

Purposes of Signs. Jehovah gave signs as an assurance of truthfulness and dependability of his words. (Jer 44:29; 1Sa 2:31-34; 10:7, 9; 2Ki 20:8-11) They demonstrated God’s backing of Moses or other servants (Ex 3:11, 12; compare Jg 6:17, 20-22), of an apostle (2Co 12:12), of the Christian congregation (1Co 14:22).

Signs were not essential to prove God’s backing, as is seen in the case of John the Baptizer. (Joh 10:41; Mt 11:9-11) Also, a false prophet might perform a sign, but he could be identified as false by the means Jehovah provided.​—De 13:1-5; 18:20-22; Isa 44:25; Mr 13:22; 2Th 2:9; Re 13:13, 14; 19:20.

Certain signs are reminders, remembrancers, memorials. (Ge 9:12-14; 17:11; Ro 4:11) The Sabbaths and the Passover constituted memorial signs for the Jews. (Ex 13:3-9; 31:13; Eze 20:12, 20) A sign of a literal or symbolic nature could serve as an identification.​—Nu 2:2; Ex 12:13.

A Sign Demanded of Jesus. During Jesus’ ministry he performed numerous signs that helped many to believe in him. (Joh 2:23) But the signs did not produce faith in hardhearted ones. (Lu 2:34; Joh 11:47, 53; 12:37; compare Nu 14:11, 22.) When on two occasions religious leaders asked Jesus to display to them a sign from heaven, they likely were demanding that he perform, as proof that he was the Messiah, the sign foretold at Daniel 7:13, 14, namely, the “son of man” appearing with the clouds of the heavens to take his Kingdom power. But it was not God’s time for that prophecy to be fulfilled, and Christ would not perform a showy display merely to gratify their selfish demand. (Mt 12:38; 16:1) Rather, he told them that the only sign that would be given them was “the sign of Jonah the prophet.” (Mt 12:39-41; 16:4) After about three days in the belly of a huge fish, Jonah had gone and preached to Nineveh. Jonah thereby became a “sign” to the capital of Assyria. Jesus’ generation had “the sign of Jonah” when Christ spent parts of three days in the grave and was resurrected after which his disciples proclaimed the evidence of that event. In this, Christ was a sign to that generation, but even that did not convince most of the Jews.​—Lu 11:30; 1Co 1:22.

Sign of Christ’s Presence. Shortly before Jesus’ death his apostles asked him: “What will be the sign of your presence and of the conclusion of the system of things?” (Mt 24:3; Mr 13:4; Lu 21:7) There were distinct differences between this question and the requests for a sign that the religious leaders had made. While right there, able to see him and his works, those leaders would not accept him as Messiah and King-Designate. (Joh 19:15) Once they asked for a sign “to tempt him” (Lu 11:16); also some may have been infected with idle curiosity about Jesus’ signs, as was Herod. (Lu 23:8) Quite the opposite, the disciples who asked about the sign of Christ’s presence already accepted him as Messiah and King. (Mt 16:16) But Jesus had said that the Kingdom was “not coming with striking observableness.” (Lu 17:20) Consequently (though the apostles mistakenly believed that the Kingdom would be established on earth; Ac 1:6), at the arrival of the Kingdom they did not want to be like the Jewish leaders​—blind to Jesus’ presence. Accordingly, they asked, not for a miraculous sign to be performed right there, but what the future identifying sign would be.

In response Jesus described a composite “sign,” one made up of many evidences, including wars, earthquakes, persecution of Christians, and a preaching about the Kingdom. (Mt 24:4-14, 32, 33) The destruction of Jerusalem and its temple was under consideration when the disciples asked Jesus for the “sign” (Lu 21:5-7), and his reply gave prophecies that applied to Jerusalem and Judea, which were fulfilled during their lifetime. (Lu 21:20; Mt 24:15) But his answer also dealt with the establishment of the Kingdom of God and its effects on all mankind.​—Lu 21:31, 35.

 “Sign of the Son of man.” On that same occasion Jesus said to his disciples: “And then the sign of the Son of man will appear in heaven, and then all the tribes of the earth will beat themselves in lamentation, and they will see the Son of man coming on the clouds of heaven with power and great glory.” (Mt 24:30; Lu 21:27) Just before this comment he had spoken of the prophet Daniel. (Mt 24:15; Da 9:27; 11:31) And from the expression Jesus here used it is evident that he was now referring back to Daniel 7:13, 14, where the vision depicted “with the clouds of the heavens someone like a son of man” gaining access to “the Ancient of Days” and receiving a ‘kingdom that will not be brought to ruin.’ This linked “the sign of the Son of man” with the time when Jesus would be exercising Kingdom power. Jesus applied the expression “Son of man” and the prophecy at Daniel 7:13, 14 to himself.​—Mt 26:63, 64; Mr 14:61, 62.

About 96 C.E., 26 years after the destruction of Jerusalem, John wrote about things that would take place in the future, and he saw in vision Jesus Christ “coming with the clouds, and every eye will see him, and those who pierced him.” (Re 1:1, 7) Hence, both this statement about something that was to take place after 96 C.E. and what Christ said about “the sign of the Son of man” referred to Jesus as coming in the clouds and as being seen by all people. (See CLOUD.) It should be noted, however, that while the Greek verb ho·raʹo, “see,” used at Matthew 24:30 and Revelation 1:7, can mean literally to “see an object, behold,” it can also be used metaphorically, of mental sight, to “discern, perceive.”​—A Greek-English Lexicon, by H. Liddell and R. Scott, revised by H. Jones, 1968, p. 1245, col. 1.

For a comparison of “miracles,” “portents,” and “signs,” see MIRACLES; PORTENT.