Definition of "remainer"

The government’s “bullish” and “macho” approach to Brexit should not stop Conservative backbenchers from tabling amendments to the crucial repeal bill, a leading Tory remainer has said.

2017 September 4, “End ‘macho’ Brexit posturing, Anna Soubry urges May”, in The Guardian‎

The reason this once-devout remainer doggedly sticks to these lines is obvious: even if opinion polling suggests that residual popular belief in Brexit is now ebbing away, the Labour party has to secure the support of people who voted leave in 2016, switched from Labour to the Tories in 2019, and would supposedly greet any talk of revisiting the basics of Brexit with anger and dismay.

2023 January 1, John Harris, “The wreckage of Brexit is all around us. How long can our politicians indulge in denial?”, in The Guardian‎

The ſide of a Hexagon or Radius being given, the ſide of a Decangle or ſubtenſe of 30 deg. is alſo given ; for by the 19 of the ſecond, the Semi-radius being deducted from the ſquare root of the ſquares of Radius and the half Radius added together, the remainer is the ſide of a Decangle.

1658, John Newton, Trigonometria Britanica‎, page 9