What is verb form of anger?

The Word 'anger' is both a verb (anger, angers, angering, angered) and a noun (anger, angers).

Examples of the verb 'anger':

You know that playing in the street will anger the neighbors.

He angers at the least mention of the political situation.

Some vandals have been angering the merchants with graffiti.

Mother angered my boyfriend by inferring that his gift was cheap.