'Thwarter' definitions:

Definition of 'thwarter'

(from WordNet)
noun
Someone who systematically obstructs some action that others want to take [syn: obstructionist, obstructor, obstructer, resister, thwarter]

Definition of 'Thwarter'

From: GCIDE
  • Thwarter \Thwart"er\, n. (Far.) A disease in sheep, indicated by shaking, trembling, or convulsive motions. [1913 Webster]