13世紀にロンドンにあった精神障害者のための病院、ベツレヘムの聖マリア病院（Hospital of Saint Mary of Bethlehem）から。
英語の語源
bedlam
bedlam: [15] The word bedlam is a contraction of Bethlehem. It comes from the Hospital of St Mary of Bethlehem founded in 1247 by Simon FitzMary, Sheriff of London, as the Priory of St Mary Bethlehem. Situated outside Bishopsgate, in the City of London, the hospital began to admit mental patients in the late 14th century. In the 16th century it officially became a lunatic asylum. The word bedlam came to be used for any ‘madhouse’, and by extension for a ‘scene of noisy confusion’, in the 17th century.
bedlam (n.)
"scene of mad confusion," 1660s, from colloquial pronunciation of "Hospital of Saint Mary of Bethlehem" in London, founded 1247 as a priory, mentioned as a hospital 1330 and as a lunatic hospital 1402; converted to a state lunatic asylum on dissolution of the monasteries in 1547. It was spelled Bedlem in a will from 1418, and Betleem is recorded as a spelling of Bethlehem in Judea from 971.
例文
1. The crowd went absolutely mad.It was bedlam .
人々はすっかり気が狂ってしまった。めちゃくちゃになった。
2.It was bedlam at our house on the morning of the wedding.
結婚式の朝、私たちの家は騒然としていた。
3.He is causing bedlam at the hotel.
彼はホテルを混乱させている。
4.When the teacher was called away the classroom was a regular bedlam .
先生が呼び出されると、教室は大騒ぎになった。
5. What's happening in that room? It's ( like ) bedlam in there.