'Upside down' definitions:

Definition of 'upside down'

From: WordNet
adverb
In an inverted manner; "the box was lying on the floor upside down"

Definition of 'Upside down'

From: GCIDE
  • Upside down \Up"side down`\, adv. in such a manner that the part normally pointed upward is pointed downward; same as upsidown and upsodown. [PJC]

Definition of 'Upside down'

From: GCIDE
  • Upside \Up"side`\, n.
  • 1. The upper side; the part that is uppermost. [1913 Webster]
  • 2. the benefits; the positive features; -- said of a situation or event that has both positive (good) and negative (bad) aspects. [PJC]
  • To be upsides with, to be even with. [Prov. Eng. & Scot.] --Sir W. Scott. --T. Hughes.
  • Upside down. [Perhaps a corruption of OE. up so down, literally, up as down.] With the upper part undermost; hence, in confusion; in complete disorder; topsy-turvy. --Shak. [1913 Webster]
  • These that have turned the world upside down are come hither also. --Acts xvii. 6. [1913 Webster]

Synonyms of 'upside down'

From: Moby Thesaurus