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mightly

/ˈmaɪt li/ adjective

Origin

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”).

From Wiktionary, via Kaikki.org (CC BY-SA)