UPSIDE

top, top side, upper side, upside

(noun) the highest or uppermost side of anything; “put your books on top of the desk”; “only the top side of the box was painted”

Source: WordNet® 3.1

Noun

upside (plural upsides)

the highest or uppermost side or portion of something

a favourable aspect of something that also has an unfavourable aspect

an upward tendency, especially in a financial market etc

Antonyms

• downside

Preposition

upside

(informal) On the top of.

Source: Wiktionary

Up"side`, n.

Definition: 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. Etym: [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 Unabridged Dictionary 1913 Edition