i-adjective
Describes a vague, unsettling feeling that something is wrong or threatening, often without a clear reason. Similar to 不気味 but with a stronger sense of underlying dread.
その廃屋は底気味悪い雰囲気に包まれていた。
The abandoned house was wrapped in an eerie atmosphere.
彼の笑顔が底気
His smile felt creepy.
不気味 is more common and neutral for 'eerie' or 'uncanny'. 底気味悪い emphasizes a deeper, more instinctive sense of dread or wrongness.
Compound of 底 (そこ, 'bottom, depths') + 気味悪い (きみわるい, 'creepy, giving a bad feeling'). The 底 element adds a nuance of something deeply unsettling, as if coming from the depths.