What do you wear in bed? Do you sleep in your birthday suit (=naked) or do you prefer to have something on like a nightie (informal word for nightdress), a onesie (an all-in-one item of clothing that covers your body, arms and legs) or pyjamas?
The word pyjamas derives from the Persian paijama. The original paijama are loose, lightweight trousers with draw-string waistbands worn in Asia by both men and women. In the UK, pyjamas are made up of two pieces – a pair of trousers and a top – and are worn in bed.
For British children, there are lots of pet abbreviations, among them ‘jamas’, ‘p-jays’, ‘jimmy jams’ and ‘jimmies’. They differ between families and whatever word you’re brought up with is correct and the other terms are weird.