undoubtedly

The word “undoubtedly” means without any doubt; certainly. In plain terms, used to say something is certainly true, with no room for doubt.

“Undoubtedly” is pronounced uhn-DOW-tihd-lee (/ʌnˈdaʊtɪdli/ in IPA).

Here is “undoubtedly” used in a sentence: “This is undoubtedly the best meal I've had all year.”

“Undoubtedly” is an adverb.

The word “undoubtedly” comes from Middle English. From Middle English undoutedly, built from undoubted plus -ly.

“Undoubtedly” is a fairly common word in modern English, usually learned at around the B2 level.

"Undoubtedly" expresses full certainty with no room for doubt, while "probably" signals likelihood but leaves open the chance of being wrong. Choosing "undoubtedly" makes a statement far stronger than "probably."

Both mean without doubt, but "undoubtedly" is more emphatic and common in modern writing, while "doubtless" can sometimes carry a hint of assumption, closer to "presumably." In most contexts they are interchangeable, as in "she will undoubtedly succeed."

As an adverb, "undoubtedly" is flexible: it can open a sentence ("Undoubtedly, he was right"), sit before the main verb ("he undoubtedly knew"), or follow a form of "be" ("she was undoubtedly correct"). Placing it next to the idea it emphasises usually reads most naturally.

"Undoubtedly" suits both formal and everyday writing, but it is especially common in academic and persuasive contexts where a writer wants to signal certainty. In casual speech, people often prefer shorter words like "definitely" or "for sure."