also: くっそ · くそー
interjection
shit!; damn!
Vulgar interjection expressing frustration, anger, or disappointment. Equivalent to くそ but with a clipped, emphatic feel.
See also: くそ
くそっ、また負けた！
Damn, I lost again!
くそっ、財布を忘れた。
Shit, I forgot my wallet.
くそ is the base form, used both as an interjection and a prefix. くそっ is a more emphatic, clipped interjection, while くっそ is a geminate variant often used as a prefix.
Derived from くそ (kuso, 'feces'), used as an expletive. The geminate form くっそ adds emphasis through consonant lengthening.