Goo (noun)

1. A sticky, slimy, or viscous substance.
2. Something that is vague, ill-defined, or difficult to understand.

Origin:

Originated in the late 19th century, probably as a shortened form of gooey.

Examples:

1. The goo from the jar of jelly had smeared all over the countertop.
2. The instructions for assembling the toy were so confusing, it was like trying to make sense of a bunch of goo.
3. The baby had smeared goo all over her face, hands and clothes.
4. The goo on the ground was the result of spilled oil.
5. The goo in the mixture was making it hard to stir.