Definition of upside down

< upside

upside-down cake >

upside down

ADVERB:

1. So that the upper or right side is down: turned upside down.
2. In great disorder.

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ETYMOLOGY:
Alteration of Middle English up so doun, up as if down : up, up ; see up + so, as if ; see so¹ + doun, down ; see down¹

OTHER FORMS:
upside-down  (psd-doun) KEY (Adjective)