WordWeb Online

1. Indicating opposition or resistance
   - counter
    
2. Characterized by antagonism or antipathy
   "slaves antagonistic to their masters"
   - antipathetic, antipathetical
    
3. Arousing animosity or hostility
   "his antagonistic brusqueness"; "Europe was antagonistic to the Unites States"
    
4. Used especially of drugs or muscles that counteract or neutralize each other's effect
   - incompatible
    
5. Incapable of harmonious association

See also: alienating, antacid, antagonism, antagonist, antagonistically, antiphlogistic, hostile, incompatible, negative

Antonym: conciliatory, synergistic

Encyclopedia: Antagonistic