Any 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.
Excessive, showy sentimentality.
To apply goo to something.
They gooed their hair with some fragrant styling product.
An example of baby talk.
The infant's goos and gahs were endearing.
To produce baby talk.
The baby gooed while daddy made sappy faces at it.