1. To cause slight irritation to (another) by troublesome, often repeated acts.
2. Archaic To harass or disturb by repeated attacks.

Synonyms: These verbs mean to disturb or trouble a person, evoking moderate anger. Annoy refers to mild disturbance caused by an act that tries one's patience: The sound of the printer annoyed me.
Irritate is somewhat stronger: I was irritated by their constant interruptions.
Bother implies imposition: In the end, his complaining just bothered the supervisor.
Irk connotes a wearisome quality: The city council's inactivity irked the community.
Vex applies to an act capable of arousing anger or perplexity: Hecklers in the crowd vexed the speaker.
Provoke implies strong and often deliberate incitement to anger: His behavior provoked me to reprimand the whole team.
Aggravate is a less formal equivalent: "Threats only served to aggravate people in such cases" (William Makepeace Thackeray).
Peeve, also somewhat informal, suggests a querulous, resentful response to a mild disturbance: Your flippant answers peeved me.
To rile is to upset and to stir up: It riled me to have to listen to such lies.