noun
exhibition room; gallery
A room or hall in a museum, gallery, or similar institution where items are displayed for public viewing.
博物館の展示室で恐竜の化石を見た。
I saw a dinosaur fossil in the museum's exhibition room.
noun
A commercial space where products are displayed for customers to view, often in a retail or wholesale context.
I went to the car manufacturer's showroom to see the new models.
ショールーム is a direct loanword for showroom, often used in commercial contexts, while 展示室 can cover both museum and commercial settings.
Compound of 展示 (display, exhibition) + 室 (room). The reading is standard on'yomi.