unfriendly in WordNet English dictionary

1. very unfavorable to life or growth
   "a hostile climate"; "an uncongenial atmosphere"; "an uncongenial soil"; "the unfriendly environment at high altitudes"
   hostile  uncongenial  unfriendly 
   
2. not friendly
   "an unfriendly act of aggression"; "an inimical critic"
   unfriendly  inimical 
   
3. not disposed to friendship or friendliness
   "an unfriendly coldness of manner"; "an unfriendly action to take"
   unfriendly 
   
4. not easy to understand or use
   "user-unfriendly"
   unfriendly