i-adjective
dangerous; risky; unreliable; dodgy
Emphatic, colloquial form of 危ない. Often implies something looks precarious, unstable, or untrustworthy. Can describe physical danger, uncertain situations, or unreliable people/things.
あの橋は古くて危なっかしいから、渡らないほうがいい。
That bridge is old and looks dangerous, so you'd better not cross it.
彼の運転はいつも危なっかしい。
His driving always seems reckless.
その計画は危なっかしいから、もっと慎重に進めよう。
That plan is risky, so let's proceed more carefully.