What does crucially mean?
Crucially is an adverb meaning 'in a way that is of decisive or vital importance'. It does two jobs in modern English. Most often it stands at the front of a sentence or clause — 'Crucially, the data was never backed up' — to signal that the point about to be made outweighs everything else around it; writers and speakers use it to direct attention to the single fact on which an argument turns. Less often it sits beside a verb to show that something hinges decisively on a particular factor, as in 'the outcome depends crucially on funding'. The word derives from crucial, which itself comes from the Latin crux, meaning cross — the image of a decision hanging on a single point. Common across British and American English and comfortable in both formal and everyday registers, crucially is indispensable in journalism, academic writing, and persuasive speech, wherever one consideration must be marked as the one that truly matters.
adverbIn a way that is of decisive or vital importance; used to emphasize that a following statement is especially significant. Also used to introduce an additional point that matters greatly.
- Used to say that something is of decisive or vital importance: 'Crucially, she had kept a copy of the contract.'
- In a manner involving a decisive or critical factor: 'The plan depended crucially on good weather.'
"Crucially, the witnesses' accounts matched in every detail."
"Crucially, the new evidence contradicted every earlier account."
"The success of the treatment depends crucially on early diagnosis."
Crucially traces back to crux — Latin for 'cross' — the same root behind 'crucify', which is why something crucial literally hangs on a decisive point.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of crucially
Crucially comes from the adjective crucial, borrowed into English in the early 18th century from Latin crux, crucis, meaning 'cross'. The original sense was anatomical — the 'crucial ligament' resembling a cross — before the word shifted to mean 'of decisive importance', as if a matter turned on a single cross-like point. The adverb formed with the regular -ly suffix. Its cognates include crux itself and other words built on the same Latin root, such as crucifix and cruciform.
Related word forms
How crucially is actually used
Register-neutral but frequent in formal writing, journalism, and academic argument, where it flags the most important point in a chain of reasoning. When it begins a sentence or clause ('Crucially, ...'), it acts as a sentence adverb highlighting what follows; placed mid-sentence near a verb ('depends crucially on'), it modifies how something relies on a factor.
Easily confused with crucially
"Crusially" is not a standard English word; "crucially" derives from Latin crux (cross), meaning decisive or vital, whereas any spelling with "s" is simply incorrect.