1) By a long way 2) By far 3) Considerably 4) Crucially 5) Decisively 6) Essentially 7) Evocatively 8) Greatly 9) Immensely 10) Importantly 11) In a significant manner 12) Meaningfully 13) Much 14) Noticeably 15) Substantially 16) To a great extent 17) To a large extent 18) Very much 19) Vitally Found on https://www.crosswordclues.com/clue/significantly