Doubtlessly

Part of speech: adverb

Definitions

1. With an absence of doubt or uncertainty in a particular situation
2. In a way that conveys unmistakable certainty or assurance about something
3. In a manner that leaves no room for hesitation or disbelief

Etymology: "Doubtlessly" is a stacked formation: "doubtless" with the adverbial suffix "-ly" added on top. "Doubtless" itself is older, built from "doubt" and the suffix "-less," meaning "without doubt," so the word is an adverb that has been given a second adverbial ending. The Middle English form "doutelesly" shows the same process at work, with the "-ly" attached to an adjective that already described a lack of doubt. Readers who find the double ending odd are in good company, since "doubtlessly" has been criticized as redundant. The base "doubtless" already functions as an adverb in its own right, so the extra "-ly" adds nothing grammatically, which explains why many style guides prefer the shorter form. The word's history is a simple one of suffixes stacking onto a root, rather than a story of shifting meaning.

Synonyms: undoubtedly, certainly, definitely, surely, incontrovertibly

Antonyms: doubtfully, questionably, uncertainly, ambiguously, possibly