Boyd’s Bible Dictionary:
A heavy beam of hard wood, with the end sometimes shaped like a ram, used for battering down the gates and walls of a city (Ezek. 4:2; 21:22).
Concise Bible Dictionary:
Modern replica of a medieval battering ram.
The machine used anciently for knocking down gates or walls. A heavy beam was suspended by chains, at the end of which was an iron head, shaped something like a ram. The name (which in both passages is simply “ram”) may have been derived either from its shape, or from the resemblance of its action to the butting of a ram. It was pulled away from the wall and then swung heavily against it (Ezek. 4:2; Ezek. 21:22).