unaccustomably

From unaccustomable +‎ -ly or un- +‎ accustomably, in later use perhaps as an alteration of unaccustomedly.

• IPA^(key): /ˌʌnəˈkʌstəməbli/

unaccustomably (comparative more unaccustomably, superlative most unaccustomably)

1. (rare) Unusually, unexpectedly, unaccountably.
   • 1583 October, John Foxe, “The conſtitution of Thomas Arundell, agaynſt the followers of Gods truth”, in Actes and monuments of matters moſt ſpeciall and memorable happenyng in the Church […] , 4th edition, volume I, London: Iohn Daye, book V, page 529:

     Finally, becauſe thoſe things which newly and vnaccuſtomably creepeth vp, ſtandeth need of new and speedy helpe […]

   • 1651, Noah Biggs, Mataeotechnia medicinae praxeωs. The vanity of the craft of phyſick. […] , London: Edward Blackmore, →OCLC, ⁋ 230, pages 168-169:

     For the veins being now unnaturally and unaccuſtomably emptied, they do attract to ſelves forthwith, from every place, and any bloud whatſoever.

   • 1977, Edward Schultz, The citizen-soldier, a factor in the making of the decisive battle: From the limited war of Frederick the Great to the unlimited warfare of Napoleon the First‎^[1], Ottawa: University of Ottawa, →OCLC, page 24:

     The Austrian commander, Prince Charles, on receiving information concerning Frederick's advance, broke his camp at Breslau and marched toward his adversary. He was unaccustomably offering battle but only with the confidence stemming from greatly superior numbers.