What does doubtlessly mean?
Doubtlessly is an adverb meaning 'without doubt' or 'certainly', used to express firm confidence that a statement is true. It is formed from the adjective 'doubtless' — itself combining 'doubt' with the suffix '-less' — plus the standard adverbial ending '-ly'. In practice it functions as a somewhat more emphatic and formally marked alternative to 'doubtless': where 'Doubtless she knew' might sound literary or old-fashioned, 'She doubtlessly knew' reads as plainly assertive. The word appears chiefly in written and formal spoken English, lending weight to arguments, judgments, and assessments of character or fact. Its connotations are entirely positive toward certainty: to call something doubtlessly so is to remove all room for hesitation. Though less frequent than synonyms such as 'undoubtedly' or 'unquestionably', it remains fully standard in both British and American English, and writers sometimes choose it simply because its extra syllable gives a statement a deliberate, measured cadence.
adverbIn a manner free from doubt; certainly or unquestionably. Used to express confidence in the truth of a statement.
- Without doubt; certainly; used to affirm the truth or likelihood of something.
"She was doubtlessly the most qualified candidate for the position."
"The plan was doubtlessly ambitious, but no one doubted the team's ability to pull it off."
"He had doubtlessly rehearsed his speech many times before stepping onto the stage."
Despite sounding more emphatic than 'doubtless', 'doubtlessly' is actually the younger upstart — a latecomer built by tacking an adverbial '-ly' onto a word that was already doing that job.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of doubtlessly
Doubtlessly derives from 'doubt', which entered Middle English from Old French 'douter', ultimately from Latin 'dubitare' ('to waver, hesitate'). The adjective 'doubtless' — literally 'free of doubt' — was formed in English with the suffix '-less', and the adverbial '-ly' was later added to produce 'doubtlessly'. It shares its Latin root with cognates such as 'dubious' and 'indubitable', which likewise trace back through French and Latin.
Related word forms
How doubtlessly is actually used
Slightly formal in register and considerably less common than its synonym 'doubtless', which serves as both adjective and adverb. Some style guides prefer 'doubtlessly' precisely because it unambiguously marks the adverbial use. It carries a confident, affirmative tone.
Easily confused with doubtlessly
'Doubtless' is the older, more common adverb meaning the same thing, while 'doubtlessly' is its less frequent variant; 'doubtless' can also function as an adjective meaning 'certain'.