verb
BAD : I'm afraid that we're out of stock but I can book one for you.
GOOD : I'm afraid that we're out of stock but I can order one for you.
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book = reserve a seat on a plane, a room in a hotel, a table at a restaurant, etc: 'The train was packed and I wished I'd booked a seat.'
order = ask for certain goods to be sent to a shop, especially because a customer wants to buy them: 'If you want to be sure of getting a daily newspaper, it's best to order one.'