In the underwear sense, Cambridge marks “undershirt” as US English and “vest” as UK English. In American English, however, “vest” usually means a sleeveless outer garment worn over a shirt.
ReviewedEvidence2 sourcesSectionEnglish Usage
Quick answer
For upper-body underwear, use “undershirt” in US English and “vest” in UK English; in US English, “vest” usually refers to a different outer garment.
Key details
Confusion Familyregional clothing vocabulary with divergent sense
Rule FamilyBritish and American vocabulary
Termsundershirt, vest
Variant ScopeUK “vest” corresponds to US “undershirt” in the underwear sense; US “vest” normally has another clothing sense.
Further guidance
Core difference
The words are regional counterparts only for the underwear meaning.
Fast Test
If the garment is worn under a shirt for warmth, US “undershirt” and UK “vest” refer to the same category.
Usage Boundary
Do not assume “vest” is region-neutral: its common American clothing meaning differs from the British underwear sense.
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.
“Faucet” and “tap” name the same kind of water-control fitting in their shared plumbing sense. “Faucet” is the usual US term and “tap” the usual UK term.
“Flyover” and “overpass” are regional equivalents when they mean a bridge carrying one route over another. “Flyover” also has a separate aircraft-event sense, especially in American English.
“Kerosene” and “paraffin” overlap as regional names for a petroleum liquid fuel used for heating and lighting. The match is sense-specific because “paraffin” also refers to wax.
“Movie theater” and “cinema” overlap when they name a venue where people pay to watch films. Cambridge marks “movie theater” as US with UK “cinema,” while “cinema” also extends to films and filmmaking more generally, so the regional equivalence is limited to the venue sense.
