relating to or at the edge or margin

marginal notes

minor and not important; not central

it seems likely to make only a marginal difference

the cost is negligible, less than marginal

(of a decision or distinction) very narrow; borderline

a marginal offside decision

a seat in a parliament or on a council that is held by a small majority and is at risk in an election

she is defending a key marginal for the Tories

a plant that grows in water close to the edge of land

remove any dead foliage on water lilies and marginals