Horn - Vine's Expository Dictionary of New Testament Words
Horn[ 1,,G2768, keras ]
a horn," is used in the plural, as the symbol of strength,
(a) in the apocalyptic visions;
(1) on the head of the Lamb as symbolic of Christ, Revelation 5:6;
(2) on the heads of beasts as symbolic of national potentates, Revelation 12:3; Revelation 13:1, Revelation 13:11; Revelation 17:3, Revelation 17:7, Revelation 17:12, Revelation 17:16 (cp. Daniel 7:8; Daniel 8:9; Zechariah 1:18, etc.);
(3) at the corners of the golden altar, Revelation 9:13 (cp. Exodus 30:2; the horns were of one piece with the altar, as in the case of the brazen altar, Exodus 27:2, and were emblematic of the efficacy of the ministry connected with it);
(b) metaphorically, in the singular, "a horn of salvation," Luke 1:69 (a frequent metaphor in the OT, e.g., Psalms 18:2; cp. 1 Samuel 2:10; Lamentations 2:3).