(n): (usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately
(n): (usually plural) loose-fitting nightclothes worn for sleeping or lounging; have a jacket top and trousers
(n): garments designed to be worn in bed
See this map for American pronunciation.
Ah, prepositional attachment humor, good stuff.
"One morning I shot an elephant in my pajamas. How he got into my pajamas I'll never know."
- Groucho Marx.