an electric railway operating below the surface of the ground (usually in a city); "in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'"
tending or intended to correct or counteract or restore to a normal condition; "corrective measures"; "corrective lenses"
designed to promote discipline; "the teacher's action was corrective rather than instructional"; "disciplinal measures"; "the mother was stern and disciplinary"