【Worry】 ,  【annoy】 ,  【harass】 ,  【harry】 ,  【plague】 ,  【pester】 ,  【tease】 ,  【tantalize】  can all mean to torment so as to destroy one's peace of mind or to disturb one acutely.

【Worry】 stresses incessant attacking or goading and an intention or sometimes an effect of driving the victim to desperation or defeat.

【Annoy】  (see also  【ANNOY】 1 ) implies continued molesting, interfering with, intruding on, or bedeviling until the victim is angry or upset.

【Harass】 usually implies persecution, especially continued petty persecutions, or burdensome demands or exactions that drive one to distraction or exhaust one's nervous or mental power.

【Harry】  , though often used interchangeably with  【harass】 , more vividly suggests maltreatment and oppression.

【Plague】 basically implies an affliction or infliction comparable to that of a devastating epidemic disease and even with greatly weakened implications tends to suggest a tormentor and an agonized or suffering victim.

【Pester】 implies the power to 【annoy】 past endurance (as by numbers or by repetition of attacks suggestive of the discomforts of an infestation of vermin).

【Tease】 may imply repeated attempts to break down resistance by successive appeals or importunities or it may imply an attempt to provoke or upset by raillery or tormenting.

【Tantalize】 stresses the repeated awakening of expectation and then its frustration.