—doubtlessness, n./dowt"lis/, adv. Also, doubtlessly.1. without doubt; certainly; surely; unquestionably.2. probably or presumably.adj.3. free from doubt or uncertainty; certain, sure.[1300-50; ME douteles. See DOUBT, -LESS]Syn. 1, 2. DOUBTLESS, UNDOUBTEDLY, INDUBITABLY, UNQUESTIONABLY are adverbs that express certainty. DOUBTLESS, although it sometimes denotes an absolute degree of certainty, more often means "probably," "presumably," or "no doubt": She will doubtless accept the offer. UNDOUBTEDLY means "beyond doubt": undoubtedly the most prolific and popular composer of his time.INDUBITABLY and UNQUESTIONABLY both affirm an unassailable conviction; they differ only in tone, INDUBITABLY being appropriate to more formal or learned discourse and UNQUESTIONABLY appropriate in a wider range of contexts and styles: an indubitably (or unquestionably) accurate transliteration of the hieroglyphic text; unquestionably the hottest running back in the league.
* * *