marginal (Adjective) — At or constituting a border or edge. ex. "the marginal strip of beach"
marginal (Adjective) — Of questionable or minimal quality. ex. "marginal writing ability"
marginal (Adjective) — Just barely adequate or within a lower limit. ex. "a marginal victory"
marginal (Adjective) — Producing at a rate that barely covers production costs. ex. "marginal industries"
marginal (Adjective) — (statistics) of or relating to a subset of random variables (with other variables having been marginalized).
marginal (Noun) — An electoral constituency where there is only a small difference between the number of votes the leading parties expect.