Definitions of marginal:

• adjective:   producing at a rate that barely covers production costs

  Example: "Marginal industries"

• adjective:   of something or someone close to a lower limit or lower class

  Example: "Marginal abilities"

• adjective:   of questionable or minimal quality

  Example: "Marginal writing ability"

• adjective:   just barely adequate or within a lower limit

  Example: "A marginal victory"

• adjective:   of a bare living gained by great labor

  Example: "A marginal existence"

• adjective:   at or constituting a border or edge

  Example: "The marginal strip of beach"