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WORDNET DICTIONARY

Adverbial doubtlessly has 1 sense

• doubtlessly(r = adv.all) doubtless, undoubtedly - without doubt; certainly; "it's undoubtedly very beautiful"

THESAURUS

doubtlessly

absolutely, admittedly, beyond doubt, beyond question, by all odds, definitely, dollars to doughnuts, doubtless, easily, in all likelihood, in all probability, incontestably, indeed, indisputably, indubitably, irrefragably, irrefutably, like enough, likely, most likely, no doubt, out of question, positively, presumably, presumptively, probably, really, ten to one, truly, undeniably, undoubtedly, unequivocally, unquestionably, very like, very likely, without doubt

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