Example of antechamber in a large house or mansion.

An antechamber (also known as an anteroom or ante-room) is a smaller room or vestibule serving as an entryway into a larger one. The word is formed of the Latin ante camera, meaning "room before". "Antechamber" comes from the French antichambre.

In some cases, an antechamber provides a space for a host to prepare or conduct private business away from a larger party or congregation. Antechambers are often found in large buildings, homes, or mansions. They are also very common in palaces and crypts. In a theme park, an antechamber may be used to tell guests about a ride before they experience it.