To an extent or in a way that cannot be, or could not have been, imagined(adverb)
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Use "unimaginably" in a sentence
"If we "assume the Big Bang" as if it were something that happened outside the bounds of reality, then we have a universe that, magically, begins fully wound-up, comprised of potential energy in unimaginably super-concentrated form."
"Blessings on this woman because she epitomizes courage under fire in unimaginably difficult circumstances."
"The semantic web would greatly stimulate the analysis of large scientific datasets, for example -- searching for patterns in unimaginably huge swathes of information, such as a microarray or a genome, in the attempt to wrest from all that clever biology something meaningful to our meagre human brains."