pop-on-top
nounUK /ˌpɒp ɒn ˈtɒp/
US /ˌpɑːp ɑːn ˈtɑːp/
A pop-on-top is a small toy or lid that you press down to make it sit on top of something.
She put the pop-on-top on her juice bottle so it wouldn't spill.
RELATED WORDS
OTHER MEANINGS
2. A small plastic figure that pops onto the top of a pencil.
He collected a pop-on-top shaped like a rocket for his pencil.
3. A decorative topper that snaps onto a cupcake or cake.
We added a pop-on-top star to each birthday cupcake.
4. A quick-attach cover for a container that clicks into place.
The pop-on-top keeps the cereal fresh after you open the box.