mightly /ˈmaɪt li/adjective 3adverb 2forms 2 adjective3 •Mighty; competent; capable; strong; powerful.King Haco would have stay'd, notwithstanding the mightly Power he had to encounter, […] — 1711 •Substantial; weighty; of import.In touching upon these mightly results, which must attend, or soon follow, the completion of Welland Canal, [...] — 1828 •Able; able to occur; possible. adverb2 •Mightily. •Very."[...] Must have been mightly well corked." "With every possible care, probably. [...]" — 1904 formsmore mightly · most mightly