Meaning
A humorous euphemism for complete nakedness: the 'suit' of bare skin a person is born in, nearly always in the fixed phrase 'in one's birthday suit'. The joke rests on an older sense of birthday as the day on which one was born; since a newborn wears nothing, nakedness is treated as the outfit proper to that day. Humorous and mildly euphemistic, not vulgar; fixed phrase 'in one's birthday suit'. The Swift coining claim is corrected on the record: Swift wrote birthday gear. Do not confuse with the historical literal sense, a fine suit worn on a monarch's birthday in eighteenth-century Britain. Regional use: Originally British; now current in US, British and Australian English.
Origin
The OED's factsheet gives earliest evidence in 1734, in England's Genius, a London collection of jests, where a young gentleman receives a caller quite naked, saying he thought he had paid his Lordship the greatest compliment 'by receiving him in his Birth-Day Suit'; Merriam-Webster independently gives 1734. Word Histories traces the variant family: the earliest known instance is 'in his birthday clothes', dated 2 June 1732, in the diary of John Perceval, Earl of Egmont, recording Lord Peterborough's joke about a bather leaping naked from his bath to greet a visitor, and Jonathan Swift used the birthday gear variant in Strephon and Chloe (1734) - so the popular claim that Swift coined birthday suit is imprecise: his wording is gear, and the exact phrase first appears in the anonymous jest book. Smollett used it in Ferdinand Count Fathom (1753), and a separate literal eighteenth-century sense existed: a fine birth-day suit worn on the anniversary of the sovereign's birth. Wiktionary's earliest quotation lags at 1842.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- in one's birthday clothes
- in one's birthday gear
Usage Examples
- The toddler answered the door in his birthday suit while his mother chased him with a towel.
- First-time visitors soon realized everyone at the sauna sits in their birthday suit quite unselfconsciously.
- Caught by the collapsing towel, he crossed the hallway in his birthday suit, clutching a newspaper for dignity.