happening by chance or unexpectedly or unintentionally ; "with an inadvertent gesture she swept the vase off the table"; "accidental poisoning"; "an accidental shooting"偶然に、予期せずにまたは意図せずに起きる偶発的
例:with an inadvertent gesture she swept the vase off the table 迂闊な身振りで彼女はテーブルから花瓶を落とした