Etymology From Middle English mightli, myȝtly, from Old English mihtelīċ (“possible, able, capable”), from Proto-West Germanic *mahtilīk, from Proto-Germanic *mahtilīkaz, *mahtulīkaz, equivalent to might + -ly. Cognate with Swedish maktlig (“powerful”).
1
Mighty; competent; capable; strong; powerful.
King Haco would have ſtay'd, notwithstanding the mightly Power he had to encounter, […]1711, Patrick Abercromby, The Martial Atchievements of the Scots Nation:
[…] and the mightly arm of Alcher ſent him like a lion howling among the members of the dead.1770, The Lady's Magazine, page 273:
2 more examples
Antilochus joined his grief to their tears: he held the mightly hand of Achilles; for deep he groaned from his inmoſt ſoul.1793, William Russell, The History of Ancient Europe:
Month after month law-suits, instigated by the grasping white man against the helpless Indian are decided in favor of the mightly and unscrupulous white.1902, The Capital, volumes 15-17, page 2:
2
Substantial; weighty; of import.
In touching upon these mightly results, which must attend, or soon follow, the completion of Welland Canal, [...]1828, Welland Canal Company, The Welland Canal Company:
Mightly indeed must be the Titanic current of that soul which could receive one whole human, full of thoughts, affections, and emotions, into its tide and yet remain uncoloured and unchanged.1983, Elizabeth K. Helsinger, THE WOMAN QUESTION Social Issues, 1837-1883:
3
Able; able to occur; possible.
mightly
adv
Etymology From Middle English myghtely, myȝtly, from Old English mihtlīċe, equivalent to might + -ly.
1
Mightily.
2
Very.
"[...] Must have been mightly well corked." "With every possible care, probably. [...]"1904, John Ames Mitchell, The villa Claudia:
We need the best material possible, and I believe we have some mightly good material at the present time.1922, American Hospital Association, Transactions: