This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

ad. without question; beyond doubt; indubitably.

ad. OK, right-on

Without doubt; indubitably.

ad. without question and beyond doubt

ad. without question

"Yet Mr. Bush's flirtation with the term unquestionably pushed Muslim intellectuals to debate the legitimacy of its use and the cult of martyrdom that had -- and may still have -- a widespread grip on many among the faithful."

questionably    unquestionable    undoubtedly    doubtlessly