1. She is doubtless my best friend. 2. He'd doubtless heard rumours on the grapevine.

What type of word is doubtless?

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.

What does Doubtless to say mean?

adverb [ADV with cl/group] If you say that something is doubtless the case, you mean that you think it is probably or almost certainly the case.