An example of protest is when you deny that you feel the way that a person is accusing you of feeling.
An example of protest is when you carry signs and picket a workplace to show your disapproval for their bad labor practices.
Eric resigned in protest.
An example of a protest is a group of people gathering together in a public setting to show that they don't agree with a decision made by a government body.
Payment under protest.
A protest movement, a protest vote cast to show dissatisfaction with the party's front-runner.
How dare you, I protest!
The public took to the streets to protest over the planned change to the law.
- while expressing one's objections; unwillingly
Idioms and Phrasal Verbs
Origin of protest
From American Heritage Dictionary of the English Language, 5th Edition