Spoil (verb)

1. To damage or ruin something.
2. To diminish the value or quality of something.
3. To pamper or indulge excessively.
4. To decay or become rotten.

Origin:

From old french espoillier, meaning 'to plunder, despoil'.

Examples:

1. The rain will spoil the picnic.
2. The mold spoiled the bread.
3. Don't spoil the child with too many toys.
4. The food will spoil if it's not refrigerated.