adjective
1.
having the upper and lower parts reversed in position
upside-down letters
Synonyms: inverted, topsy-turvy
Related Word: reversed
2.
confused utterly even to the point of inversion of the normal or reasonable
upside-down logic that confused cause with effect
Synonyms: arsy-varsy, downside-up, topsy-turvy
Related Word: inverted, reversed; chaotic, confused, helter-skelter, jumbled, mixed-up; fouled-up, haywire, ||snafu
Contrasted words: orderly, well-ordered; logical, reasonable, sensible, sound; legitimate, plausible