noun The act of improving; advancement or growth; a bettering
noun The act of making profitable use or application of anything, or the state of being profitably employed; practical application, for example of a doctrine, principle, or theory, stated in a discourse.
noun The state of being improved; betterment; advance
noun Something which is improved
the new edition is an improvement on the old.
noun Increase; growth; progress; advance.
noun Valuable additions or betterments, for example buildings, clearings, drains, fences, etc., on premises.
noun (Patent Laws): A useful addition to, or modification of, a machine, manufacture, or composition.