doubtless

1 of 2

adverb

doubt·​less ˈdau̇t-ləs 

1

: without doubt

2

: probably

doubtless

2 of 2

adjective

: free from doubt : certain

doubtlessly adverb

doubtlessness noun

Synonyms of doubtless

Adverb

• certainly
• surely
• definitely
• sure
• probably
• clearly
• undoubtedly
• likely

Adjective

• sure
• confident
• assured
• certain
• positive

Examples of doubtless in a Sentence

Adverb

she is doubtless the one and only girl for me

doubtless you have heard this story before, but I'll tell it anyway

Adjective

another one of his doubtless predictions that will never come true

Recent Examples on the Web

Adverb

Even during the regular waterfowl seasons, hunters have doubtless seen a lone snow goose or white-fronted goose alone in a field. —Bryan Hendricks, Arkansas Online, 15 Feb. 2026

Drescher has doubtless heard the same from time to time. —Dessi Gomez, Deadline, 11 Jan. 2026

Adjective

Lastly, while there is doubtless a tradeoff between construction costs and operations, a smooth operation at the big airport this coming summer — the busiest travel season — sure as heck needs to be a priority. —The Editorial Board, Chicago Tribune, 4 Mar. 2026

Add in the doubtless significant number of people under 18 using ChatGPT (who weren't included in the sample at all), and a decent majority of OpenAI's users probably aren't old enough to remember the 20th century firsthand. —ArsTechnica, 15 Sep. 2025

Word History

First Known Use

Adverb

14th century, in the meaning defined at sense 1

Adjective

15th century, in the meaning defined above

Kids Definition

doubtless

1 of 2 adverb

doubt·​less ˈdau̇t-ləs 

1

: certainly

2

: probably

doubtless

2 of 2 adjective

: free from doubt : certain

doubtlessly adverb