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Alternative forms[edit]


copper +‎ fasten. From copper sheathing of ship hulls (to protect from damage by marine organisms. Originally copper sheathing but non-copper bolts were used, leading to corrosion. Later copper bolts (fasteners) were also used, eliminating corrosion issues. Literal sense from 18th century, metaphorical sense attested 1948.[1]



copperfasten (third-person singular simple present copperfastens, present participle copperfastening, simple past and past participle copperfastened)

  1. (transitive, historical) To protect the timbers [of a ship] with plates of copper secured with copper nails or bolts.
    • 1796, The Hull Advertiser, 9th July 1796:[1]
      She is copper-fastened and copper-bottomed, and a remarkable fine ship.
  2. (transitive, figuratively, Britain, Ireland) To reinforce, strengthen; to make permanent, embed.
    • 1948, The Evening Independent, November 1948:[1]
      We had some striking examples of what happens when a guy gets so big for his britches that any pal of his is automatically a copper-fastened genius.
    • 2010 Supreme Court rules on law translation]”, RTÉ News, May 6, 2010:
      This brings to an end a ten-year campaign by Pol O Murchú and other Irish language activists to copperfasten rights to have Irish language legislation made available . . . .

Usage notes[edit]

Particularly used attributively, as copper-fastened (less commonly, copperfastened).

Originally (in literal sense) an intensifier of copper-bottomed, meaning not only that the plates were copper, but the fasteners too.[1] In meaning close to copper-bottomed, but emphasis on security and lack of ambiguity (compare nailed down), rather than on certainty and trustworthiness.[1]

Related terms[edit]

See also[edit]


  1. 1.0 1.1 1.2 1.3 1.4 Copper-bottomed” in Gary Martin, The Phrase Finder, 1997–, retrieved 26 February 2017.
  • “A Shipwright” “Foreign Zinc PlateThe Mechanic's Magazine, Museum, Register, Journal, and Gazette (31 May 1834) Vol.21, No.564, p.136