Meaning of “margin” - Learner’s Dictionary

margin

noun [ C ] uk us /ˈmɑːdʒɪn/
AMOUNT

the difference between two amounts of time, money, etc, usually between people in a competition:

to win by a narrow/wide margin
He took third place by a margin of seven minutes.
SPACE

an empty space down the side of a page of writing:

You can make notes in the margin.
a margin of error

the amount by which a calculation can be wrong but still produce a good result:

a margin of error of 5 percent

(Definition of “margin” from the Cambridge Learner’s Dictionary © Cambridge University Press)