IMPROVEMENT Synonyms: 73 Similar and Opposite Words - Merriam-Webster
https://www.merriam-webster.com/thesaurus/improvement
WEBSynonyms for IMPROVEMENT: advance, advancement, enhancement, breakthrough, development, innovation, refinement, discovery; Antonyms of IMPROVEMENT: setback, breakdown, reduction, collapse, decrease, crash, impediment, deterioration.
DA: 77 PA: 30 MOZ Rank: 52