Definition of "goalpost"

goalpost

/ˈɡəʊlpəʊst/

noun
plural goalposts
1. (sports) One of the two vertical side poles of a goal.
  Quotations
  Some kids were having a kickabout on the grass beside the walkway, cheering, groaning, calling for the ball, absorbed in the game, a self-contained universe marked out by jackets for goalposts and invisible touchlines.
  2022, Liam McIlvanney, The Heretic, page 107
2. (sports, American football) The tall Y-shaped upright, now usually of fiberglass, at either end of the playing field, through which a football must go in order for a field goal to be scored. (They were originally H-shaped, with one wooden post on either side.)
3. A rule or target that is "moved" (changed) unfairly; see move the goalposts.
  Quotations
  […] whatever you eat, how much you drink, you know the goalposts keep moving all the time, and it's difficult to be sure that, but I don't think it's harmful, not the amount I drink.
  2012, Sarah L. Holloway, Mark Jayne, Gill Valentine, Alcohol, Drinking, Drunkenness: (Dis)Orderly Spaces, page 55