Definition of "haystack"

haystack

/ˈheɪˌstæk/

noun
plural haystacks
1. A mound, pile, or stack of stored hay.
2. (canoeing) A standing wave in a rapid.
3. (programming) The text string within which another string is searched for. (see: needle in a haystack)
  Quotations
  Both of these functions will look through the haystack for the specified needle and, if they find it, will return the portion of the string from the beginning of the needle to the end of the haystack.
  2010, Peter MacIntyre, PHP: The Good Parts, page 39
4. A dish composed of a starchy food (rice, tortillas, crackers, etc.) topped by a protein (beans, cheese, meat, etc.) in combination with fresh vegetables, assembled on the plate by the diner.