Learner's definition of MARGIN
1 : the part of a page that is above, below, or to the side of the printed part 2 : the place where something (such as a piece of land) stops : the edge of something
— often used figuratively in the phrase on the margins or (US) on the margin
We'll meet at the margin [=(more commonly) edge] of the forest.
Mountains lie at the city's northern/southern margins.
We are trying to improve medical care for poor families living on the margins of society. [=poor families who are often forgotten or ignored by society]
The business has been operating on the margins of respectability. [=has been operating in a way that is not truly respectable]
3 : an extra amount of something (such as time or space) that can be used if it is needed
◊ If you have little or no margin for/of error, it means that you need to be very careful not to make mistakes. If you have a greater margin for/of error, you can be less careful.
4 : a measurement of difference
The bullet missed his heart by a narrow/slim margin. [=the bullet narrowly missed his heart]
We lost the election by a one-vote margin. [=we lost the election by one vote]
She won by a margin of 3,000 votes.
He was the winner by a large/considerable margin.
◊ A margin of error is a number or percentage that shows how accurate a measurement is.