'atrium' originates from Latin, specifically the word 'atrium', where it referred to the central room of a Roman house and may be associated with 'ater' meaning 'black' (possibly referring to the hearth).

'atrium' passed from Latin into Medieval and Renaissance Latin usage and then into English as 'atrium'; it retained the architectural sense and later was extended in medical usage to describe a heart chamber, with the regular Latin plural 'atria' used in English.

Initially it meant 'the central hall or main room of a Roman house'; over time it broadened to include 'a large open space in a building' and was later applied in anatomy to mean 'an upper chamber of the heart'.