WordWeb Online

1. Discouraging by hindering
    
2. Preventing realization or attainment of a desire
   - frustrative, thwarting

1. Hinder or prevent (the efforts, plans, or desires) of
   "What ultimately frustrated every challenger was Ruth's amazing September surge"
   - thwart, queer, spoil, scotch, foil, cross, baffle, bilk
    
2. Treat cruelly
   - torment, rag, bedevil, crucify, dun

See also: discouraging, frustration, preventative, preventive

Type of: beset, chevvy [non-standard], chevy, chivvy, chivy, forbid, foreclose, forestall, harass, harry, hassle, molest, plague, preclude, prevent, provoke