What does "improvement" mean?

Improvement: The act of making profitable use or applicaton of anything, or the state of being profitably employed; a turning to good account; practical application, as of a doctrine, principle, or theory, stated in a discourse. "A good improvement of his reason." S. Clarke. I shall make some improvement of this doctrine. Tillotson.

Additional senses

  1. 2.The state of being improved; betterment; advance; also, that which is improved; as, the new edition is an improvement on the old. The parts of Sinon, Camilla, and some few others, are improvements on the Greek poet. Addison.
  2. 3.Increase; growth; progress; advance. There is a design of publishing the history of architecture, with its several improvements and decays. Addison. Those vices which more particularly receive improvement by prosperity. South.
  3. 4.pl. Valuable additions or betterments, as buildings, clearings, drains, fences, etc., on premises.
  4. 5.(Patent Laws) A useful addition to, or modification of, a machine, manufacture, or composition. Kent.

Sources