Oxy actually means sharp or acidic in greek. Oxygen was wrongly named like that (acid former) because it was thought to be the element to give acids their sourness but later many acids without oxygen were discovered. The key turned out to be hydrogen not oxygen

An informal nickname for the opioid Oxycodone

Or a reference to oxidation, the process by which rust is formed…

And also prOXY. Works in many levels.

Or simply oxygen.

or oxytocin

or oxymoron

that's funny :)