Careless or thoughtless; prone to making hasty mistakes or acting without sufficient attention.
彼はそそっかしくて、よく鍵を忘れる。
He's careless and often forgets his keys.
そそっかしい言い方で相手を怒らせてしまった。
I spoke thoughtlessly and ended up upsetting the other person.
あの店員はそそっかしいが、明るくて親切だ。
That clerk is careless, but cheerful and helpful.