i-adjective
terrible; dreadful; terrifying
Describes something that inspires fear or dread; can be used for real danger or exaggerated emotional reaction.
あの事故は本当に恐ろしかった。
That accident was truly terrifying.
彼の怒った顔
His angry face is frightening.
i-adjective
tremendous; amazing; startling
Only when written 恐ろしい
Often used adverbially as 恐ろしく to mean 'extremely' or 'awfully'; expresses a high degree, not literal fear. Restricted to the 恐ろしい spelling.
彼は恐ろしく速く走る。
He runs tremendously fast.
恐ろしい量の仕事が残っている。
A startling amount of work remains.