1.nounAny semi-solid or liquid substance; especially one that is sticky, gummy or slippery; frequently of vague or unknown composition, slime or a bodily fluid.
"I stepped in some goo and had a terrible time getting the sticky stuff off my shoes."
2.nounExcessive, showy sentimentality.
3.verbTo apply goo to something.
"They gooed their hair with some fragrant styling product."