“Inquiry” and “enquiry” overlap in meaning. Cambridge lists “enquiry” as a UK form of “inquiry,” so the useful distinction is regional/style preference rather than a universal right-versus-wrong rule.
ReviewedEvidence2 sourcesSectionEnglish Usage
Quick answer
“Inquiry” is widely used; “enquiry” is also a documented UK form. Follow the regional or house style required for the document.
Key details
Confusion Familyregional-spelling
Noun Variant ScopeCambridge records “enquiry” as a UK form of “inquiry,” while “inquiry” is also used in UK English.
Rule Familyregional-orthography
Termsinquiry, enquiry
Further guidance
Core difference
“Inquiry” is widely used and Cambridge also records “enquiry” as a UK form.
Fast Test
Use the spelling required by your regional or house style; do not label the documented UK form “enquiry” as an error.
Variant Boundary
The cited dictionary does not support a rigid rule that UK English must always use “enquiry” and US English must always use “inquiry.”
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
“Aging” and “ageing” are established regional spellings. Cambridge labels aging as US and ageing as UK, so the choice should follow the intended variety or house style.
“Analyze” is the standard US spelling and “analyse” is the standard UK spelling of the same verb. The distinction is regional spelling; use the form that matches the target variety or editorial style.
“Behavior” is the US spelling and “behaviour” is the UK spelling. Use the form consistent with the regional variety or editorial style of the document.
Both “canceled” and “cancelled” are standard past-tense spellings of “cancel”; US English usually uses one l, while UK English normally uses two. Cambridge records the -ll- forms and notes that US English usually uses -l-, so the difference should be presented as a regional preference rather than a correctness split.
