Concise Bible Dictionary:

In Exodus 12:22-2322And ye shall take a bunch of hyssop, and dip it in the blood that is in the bason, and strike the lintel and the two side posts with the blood that is in the bason; and none of you shall go out at the door of his house until the morning. 23For the Lord will pass through to smite the Egyptians; and when he seeth the blood upon the lintel, and on the two side posts, the Lord will pass over the door, and will not suffer the destroyer to come in unto your houses to smite you. (Exodus 12:22‑23) the “lintel” is the beam that runs along the top of a door and joins the two side-posts. The word is mashgoph, and occurs only in the above passage and in Exodus 12:77And they shall take of the blood, and strike it on the two side posts and on the upper door post of the houses, wherein they shall eat it. (Exodus 12:7), where it is translated “upper door post,” but clearly means the lintel. In 1 Kings 6:33And the porch before the temple of the house, twenty cubits was the length thereof, according to the breadth of the house; and ten cubits was the breadth thereof before the house. (1 Kings 6:3)1 The word is ayil, which is often translated “posts.” In this passage its meaning is doubtful. In Amos 9:11I saw the Lord standing upon the altar: and he said, Smite the lintel of the door, that the posts may shake: and cut them in the head, all of them; and I will slay the last of them with the sword: he that fleeth of them shall not flee away, and he that escapeth of them shall not be delivered. (Amos 9:1) and Zephaniah 2:1414And flocks shall lie down in the midst of her, all the beasts of the nations: both the cormorant and the bittern shall lodge in the upper lintels of it; their voice shall sing in the windows; desolation shall be in the thresholds: for he shall uncover the cedar work. (Zephaniah 2:14) the word is kaphtor, which is elsewhere translated “knop.” It may refer to some device placed over a door.

Strong’s Dictionary of Hebrew Words:

from 8259 in its original sense of overhanging; a lintel
KJV Usage: