WordReference Random House Learner's Dictionary of American English © 2025
ˈup•side ˈdown, adv.
WordReference Random House Unabridged Dictionary of American English © 2025- with the upper part at the bottom.
- in or into complete disorder;
topsy-turvy:turned the room upside down in their search.
up′side down′,
- with the upper part undermost.
- in or into complete disorder;
topsy-turvy:The burglars turned the house upside down. - 1300–50; re-formation (see upside) of Middle English upsedoun, earlier up so doun (see up, so1, down1; sense of so obscure)
up′side-down′ness, n.
'turn upside-down' also found in these entries (note: many are not synonyms or translations):