adverb
Used in exclamatory or interrogative contexts to express degree or extent, often with an emotional nuance.
どんなに嬉しかったか、言葉にできない。
I can't put into words how happy I was.
どんなに待っても彼は来なかった。
No matter how long I waited, he didn't come.
adverb
Used in concessive patterns with ても/でも to mean 'no matter how much' or 'even if'. Often followed by a verb or adjective in the ても form.
どんなに忙しくても、運動する時間は作るべきだ。
No matter how busy you are, you should make time to exercise.
どんなに高くても、彼はその車を買うだろう。
However expensive it is, he will probably buy that car.