Upside \Up"side`\, n. The upper side; the part that is uppermost.

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.

These that have turned the world upside down are come hither also. --Acts xvii. 6.

Source: Webster's Revised Unabridged Dictionary (1913)