In most sentences that use the word lunch, I found this word does rarely take the definite article the. For example:
I have lunch in three hours.
Shall we go out for lunch?
Let's have some lunch.
I'll take my lunch to school.
But now I wonder if this word really cannot take the definite article, and if it can, in what cases do I use the definite article and in what cases not?
And also, if the word lunch cannot take the definite article, why cannot it have it?