骚扰 means 'to harass' — it implies repeated, unwanted actions that annoy or threaten someone, often with a serious or legal connotation (e.g., sexual harassment). It is stronger and more formal than 打扰/打搅 ('to disturb, to bother'), which are everyday words for minor interruptions. 捣乱 and 闹事 focus on causing trouble or making a public disturbance, not targeted harassment.