From Middle English main stai, equivalent to main +‎ stay (rope).



mainstay (plural mainstays)

  1. A chief support.
    Agriculture is the mainstay of this country’s economy.
    • 2000, Jedrzej George Frynas, Oil in Nigeria, →ISBN:
      Oil is the mainstay of Nigeria's economy.
    • 2014, Marc C. Hochberg, ‎Alan J. Silman, ‎& Josef S. Smolen, Rheumatology, →ISBN, page 307:
      Conventional radiography has a major role in, and remains the mainstay of, initial evaluation and follow-up of rheumatologic disease.
  2. Someone or something that can be depended on to make a regular contribution.
    • 1963 January, “Motive power miscellany”, in Modern Railways, page 65:
      On the Bishops Stortford line, the crisis now seems to be over; the units designed for this service are the mainstay of the workings once again and although some of the inner suburban sets are still seen, very few L.T.S. Line units are noticeable.
    • 2004, Susan McHugh, Dog, →ISBN:
      Like show dogs, dog actors became a mainstay in European and American contexts from the early nineteenth century with the convergence of public sentiment for dogs and popular interest in training them.
    • 2010, Lamar Underwood, 1001 Fishing Tips, →ISBN:
      Crickets are a mainstay of panfishing with live bait—and a mainstay of bait shops—but they come off the hook easily and you'll be plagued by minnows and tiny fish constantly stealing your bait.
    • 2016 May 23, Ignatiy Vishnevetsky, “Apocalypse pits the strengths of the X-Men series against the weaknesses”, in The Onion AV Club[1]:
      X-Men: Apocalypse, directed by series mainstay Bryan Singer, gives Magneto, the Holocaust survivor who can control magnetic fields, and Xavier, the paraplegic telepath who tends to come off as really smug, next-to-zero shared screen time.
  3. (nautical) A stabilising rope from the top of the mainmast to the bottom of the foremast.