'Horn' in the Bible

He is not to be touched by a hand, but is to be stoned or have an arrow put through him; man or beast, he is to be put to death: at the long sounding of a horn they may come up to the mountain.

And when morning came on the third day, there were thunders and flames and a thick cloud on the mountain, and a horn sounding very loud; and all the people in the tents were shaking with fear.

And when the sound of the horn became louder and louder, Moses' words were answered by the voice of God.

And all the people were watching the thunderings and the flames and the sound of the horn and the mountain smoking; and when they saw it, they kept far off, shaking with fear.