upside down

• up so down (14th-16th centuries)
• downside up

Alteration of earlier up so down, from Middle English up-so-doun, upsedowne, upsadowne (“upside down”), equivalent to up +‎ so +‎ down ("up as down").

• IPA^(key): (careful speech) /ˌʌpsaɪd ˈdaʊn/, (fast speech) /ˌʌpsaɪˈdaʊn/

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upside down (not comparable)

1. Inverted, so that the top is now at the bottom.

   The Union flag was flying upside down, a sign of danger.

   • 1937, “A Foggy Day (In London Town)”, Ira Gershwin (lyrics), George Gershwin (music):

     For, suddenly, I saw you there / And through foggy London town / The sun was shining upside down!

2. In great disorder.

   The thief had turned the room upside down.

   c. 1597 (date written), William Shakespeare, “The First Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene i]:

   This house is turned upside down since Robin Ostler died.

• (inverted): bottom-upwards, topsy-turvy

upside down (not comparable)

1. Inverted; turned so that the top is at the bottom.

   The pattern resembled an upside down letter W.

2. In great disorder.
   • 1901, Amelia Edith Huddleston Barr, The lion's whelp: a story of Cromwell's time, page 248:

     The wenches and the men have been on the streets all day, and the kitchen is upside down. You never saw the like.

3. (finance) Owing more money for something than it is worth; having negative equity.

   He's upside down on his mortgage.

• (having negative equity): underwater

• downside up