hard work

• hardwork, hard-work (both nonstandard)

hard work (uncountable)

1. Something requiring much effort to accomplish, either physical, mental or emotional; labor; toil. (This entry is a translation hub.)
   • 1958 July, J. P. Wilson, “Scottish Soliloquy”, in Railway Magazine, pages 493, 495:

     Compact strongly-built engines, with a capacity for hard work, they were, perhaps, not in the front rank of handsome locomotives, yet withal were pleasing to the eye.

   • 2011 November 12, Phil McNulty, “International friendly: England 1-0 Spain”, in BBC Sport‎^[1]:

     Capello was keen to use Phil Jones, normally a defender, in central midfield - but it was hard work for the Manchester United teenager and his England colleagues in the first half as Spain predictably dominated possession.

• hard labor
• work hard