doubtless
adv. sent.adv. without any doubt. You use this to say that something is almost certainly true, even if you cannot prove it yet.
adv. used to express that something is very likely or certain to happen or be true. Often used to concede a point before introducing a contrasting idea.
He will doubtless succeed in his new job.
The new policy will doubtless cause some confusion among the staff during the first few weeks of implementation.
While the critic acknowledged the film's technical brilliance, he noted that it would doubtless struggle to find a wide audience due to its experimental narrative structure.
From Middle English douteles, dowteles, equivalent to doubt + -less.
Sentence adverb — often placed after the first auxiliary verb or at the start of a clause to indicate the speaker's certainty.