doubtless /ˈdʌʊ̯tləs/adjective 2adverb 1 adjective2 •Characterized by or experiencing no doubt at all, certain; undoubted; undoubting.There are those who have doubtless faith in revelation. — 1880 •(no longer used) Free from fear or suspicion.And, pretty childe, sleepe doubtlesse, and secure, / That Hubert for the wealth of all the world, / Will not offend thee. — 1596 adverb1 •Without doubt; certainly; definitely; very probably, in all likelihood; doubtlessly.[…] And, doubtless, unto thee is given A life that bears immortal fruit In such great offices as suit The full-grown energies of heaven. — 1850