na-adjective, noun
Describes a person, situation, or thing that seems untrustworthy or not quite right. Often used in the phrase 胡散臭い (うさんくさい).
あの男は胡散な感じがする。
That man gives off a suspicious vibe.
胡散な話に乗ってはいけない。
Don't get involved in shady deals.
The origin is uncertain. The kanji 胡 and 散 are used phonetically (ateji) to represent the sound うさん. The word is now mostly encountered in the compound 胡散臭い.