Pajamas and pyjamas both refer to loose-fitting clothes worn for sleep. Pajamas is the preferred spelling in American English, while pyjamas is preferred in the main varieties of English from outside North America. Canadian usage in this century is inconsistent, though pyjamas appears to have the edge.
Outside the U.S.
Munshaw-Luhar says the shops also stock sherwani suits and kurta pyjamas for men and expensive wedding outfits. [Sydney Morning Herald]
What I always do is to retire to the bedroom and change into my pyjamas. [Financial Times]
Padding around the house in pyjamas and bunny slippers won’t do your sexual relationship any favours either. [Ottawa Citizen]
He’s wearing red silk pajamas, a black smoking jacket, black slippers, white socks. [Vanity Fair]
The nightwear comes in a handful of styles and colors and includes nightgowns and pajamas. [Chicago Tribune]
Many wore pajamas, masks or wigs. [Wall Street Journal]