to enhance (something) in value or quality; to make (something) better
to increase the value of (land or property), esp by cultivation or the erection of buildings
to become better; to make progress
(usu + on/upon) to produce or achieve something better than a previous version, result, etc
We must try to improve on last week's score
improvability /-ʹbiliti/ noun
improvable adj
improver noun
[Anglo-French emprouer to invest profitably, from Old French en-1 + prou advantage, from late Latin prode: see proud]