1N-COUNT (露天)干草堆,干草垛 A haystack is a large, solid pile of hay, often covered with a straw roof to protect it, which is left in the field until it is needed. (露天)干草堆,干草垛
2PHRASE 落进干草垛里的一根针(比喻如大海捞针般难找的东西) If you are trying to find something and say that it is like looking for a needle in a haystack, you mean that you are very unlikely indeed to find it. 落进干草垛里的一根针(比喻如大海捞针般难找的东西)