Filed from 27 published puzzles

HARD

Set to 22 different clues across 27 published puzzles, most often “Difficult” — The New York Times, Monday, 21 April 2008.

4 letters

Every clue on record, most used first

  • Difficult3 times

    The New York Times — Monday, 21 April 2008

  • Brain-busting2 times

    The New York Times — Sunday, 24 January 2010

  • Rocklike2 times

    The New York Times — Monday, 17 March 2008

  • Granitelike2 times

    The New York Times — Tuesday, 3 July 2001

  • Fatiguingonce

    The New York Times — Thursday, 5 May 2011

  • ___ as a diamondonce

    The New York Times — Tuesday, 28 April 2009

  • Obdurateonce

    The New York Times — Wednesday, 23 January 2008

  • Compactonce

    The New York Times — Saturday, 8 September 2007

  • Steellikeonce

    The New York Times — Monday, 4 June 2007

  • Not liquidyonce

    The New York Times — Sunday, 31 December 2006

  • Like some cideronce

    The New York Times — Thursday, 7 April 2005

  • Verifiable, as factsonce

    The New York Times — Sunday, 11 April 2004

Other answers to these clues