goalpost
Concise Oxford English Dictionary © 2008 Oxford University Press:
goalpost/ˈɡəʊlpəʊst/
▶noun either of the two upright posts of a goal.
– phrases
move the goalposts unfairly alter the conditions or rules of a procedure during its course.
move the goalposts unfairly alter the conditions or rules of a procedure during its course.
'goalpost' also found in these Oxford entries:

