HAYSTACK Meaning of HAYSTACK in English hay ‧ stack /ˈheɪstæk/ BrE AmE ( also hayrick ) noun [countable] a large, firmly built pile of hay ⇨ like looking for a needle in a haystack at ↑ needle 1 (7) Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012