I'll have/a the roast chicken.

[kadioguy]

[From the Oxford Picture Dictionary 3rd ed.]

Some of them use "a", while others use "the", why?
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Me:
A: Are you ready to order?
B: I think so. I'll have the roast chicken/I'll have a roast chicken.

Do both "the" and "a" work here? And why?

ChatGPT: Using "the" implies that there is only one option of roast chicken on the menu or that it is a well-known or previously mentioned dish. It also gives a sense of specificity and emphasis on the particular dish.

Using "a" implies that the speaker is not particular about which roast chicken they receive. It is a more general or non-specific way of ordering the dish.

In some restaurants, there may be different variations of roast chicken available on the menu, such as roasted chicken with herbs, roasted chicken with vegetables, or roasted chicken with gravy. In this case, using "a" before "roast chicken" would indicate that the speaker is not being specific about which type of roast chicken they want.
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So both would work. Do you agree?

 

[Tarheel]

Yes. If they have several choices of roast chicken then "a" is possible.

 

[SoothingDave]

Keeping in mind that even the smallest chickens are about 4 lbs (1.8 kg), it's kind of odd to order a chicken.

(Unless you are Jake Blues, who is known for ordering 4 fried chickens. And a Coke.)

 

[Barque]

"The roast chicken" means "the roast chicken dish that's on the menu".

"A roast chicken" could conceivably be used there to mean "a dish of roast chicken". But "the" is much more likely.

However, with cheese sandwiches or coffee or soup, you're more likely to hear "a". That's possibly because they're more commonplace.

 

[Barque]

When I say 'commonplace', I mean that things like cheese sandwiches are fairly simple, and are prepared in much the same way and with much the same ingredients wherever you go. Roast chicken on the other hand is likely to have more variation in ingredients, style of cooking, etc.

 

[jutfrank]

I'll repeat what Barque has already said in post #4: Using the refers specifically to the menu item.