1. suspicious; dubious; questionable; dodgy; shady; fishy
それって、怪しくない？Isn't that suspicious?
2. doubtful; unsure; uncertain; unlikely; implausible
そもそも完成するかどうかも怪しいけれど。It's doubtful whether it will even be completed in the first place.
3. untrustworthy; unreliable; clumsy; awkward; shaky; poor
最近、記憶が怪しい。My memory has been unreliable lately.
4. strange; weird; eerie; spooky; uncanny
夜の墓地は怪しい雰囲気だった。The cemetery at night had an eerie atmosphere.
5. ominous (e.g. weather); threatening; dangerous (e.g. financial situation); uncertain
あの会社は経営が怪しいらしい。I hear that company is on shaky ground financially.
6. suspicious (of a potential amorous relation)
二人の仲が怪しいと噂になっている。There are rumors that something is going on between the two of them.
7. mysterious; bewitching; alluring; enticing; enchanting
also 妖しい
彼女には怪しい魅力がある。She has a bewitching charm.