From The Collaborative International Dictionary of English v.0.48 [gcide]:
Unfriendly \Un*friend"ly\, a.
1. Not friendly; not kind or benevolent; hostile; as, an
unfriendly neighbor.
[1913 Webster]
2. Not favorable; not adapted to promote or support any
object; as, weather unfriendly to health.
[1913 Webster] -- Un*friend"li*ness, n.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
unfriendly
adj 1: not easy to understand or use; "user-unfriendly" [ant:
friendly]
2: not disposed to friendship or friendliness; "an unfriendly
coldness of manner"; "an unfriendly action to take" [ant:
friendly]
3: not friendly; "an unfriendly act of aggression"; "an inimical
critic" [syn: unfriendly, inimical]
4: very unfavorable to life or growth; "a hostile climate"; "an
uncongenial atmosphere"; "an uncongenial soil"; "the
unfriendly environment at high altitudes" [syn: hostile,
uncongenial, unfriendly]