If something is spumy, it has a lot of foam or bubbles on top.
Spumy things are often found in the kitchen or in nature, like on the ocean or in a waterfall.
Examples:
The spumy water splashed on the rocks.
The spumy milk overflowed from the glass.
The spumy bubbles were white and fluffy.
The spumy bath was so full of bubbles, I couldn't see my toes!
The spumy fountain sprayed water and foam everywhere.
The spumy waves crashed against the shore.