Cambridge: used to emphasize a situation, quality, or type of behaviour（用於強調狀況或品行）簡直就是，極其
The party was nothing short of a disaster. => 加名詞
His achievements as a political reformer have been nothing short of miraculous => 加形容詞
這邊注意到，前面是複數，而後面是單數，概念上就是把前面包成一個整體放到 a miracle 下面。