undoubtlessly

English

Etymology

From un- +‎ doubtlessly.

Adverb

undoubtlessly (comparative more undoubtlessly, superlative most undoubtlessly)

1. (nonstandard) Synonym of without a doubt
   • 1920, American Magazine, volume 90, page 70:

     “Now, little girl,” he says, with a fatherly smile (he'll soon be twenty-six), “tell me just what your difficulty is, and undoubtlessly we'll fix it up in a jiffy!”