marginal
adjective
uk/ˈmɑːdʒɪnəl/ usvery small in amount or effect:
a marginal improvement/increase/decrease The report suggests that there has only been a marginal improvement in women's pay over the past few years.
We have doubled our computing power at a marginal extra cost.
The fuel-price increase will have only a marginal effect on the road fuel market.
not very important:
Manufacturing is only a marginal sector in the UK these days.
Their contribution to business strategy has been marginal.
ECONOMICS
producing just enough income to cover the costs of making and selling something:
Their sales volumes are marginal.
For years, these marginal operators have only just managed to keep going and banks will not look at them favorably.
POLITICS
a marginal seat (= area with one political representative) is one in which a politician has won by a small number of votes, so it is fairly likely to be won by another party when there is an election:
These MPs have rural seats, many of them marginal.